Two years ago, Sean T. O’Donovan was a nobody at Boston City Hall, a former Somerville alderman and a lawyer handling personal injury and drunken-driving cases from a modest office in Ball Square.

But with Martin J. Walsh’s election as mayor, O’Donovan gained powerful new connections in Government Center. Not only has he known Walsh for 20 years, but O’Donovan’s childhood buddy, high school classmate, and former longtime law partner, Eugene L. O’Flaherty, became the city’s top lawyer.

Under the new administration, O’Donovan has emerged as an influential player and a product salesman in Boston City Hall, enjoying direct access to top officials, according to hundreds of e-mails between O’Donovan and city employees, which were obtained by the Globe through a records requestand offer a breathtaking how-to guide for leveraging political relationships.

O’Donovan’s clients with business before the city include the Dabbah family of Switzerland, whose development company is proposing a luxury condo tower overlooking Boston Common. He’s handling business before the Boston Licensing Board for a restaurant conglomerate, shepherding clients through the Mayor’s Office of Consumer Affairs and Licensing, and arguing for relief from the Zoning Board of Appeal for builders and developers.

But that’s not all. The Somerville lawyer is also selling industrial cleaning products to the city by the barrel. He’s pushing solar-powered garbage cans to the top echelon of the Public Works Department. His pitch to city officials for an “amazing’’ product that “will forever solve each and every pothole’’ reads like a late-night infomercial.

And along the way he has found time to tap political contacts for his family, lobbying the mayor’s office for help securing his nephew a recommendation to the US Naval Academy.

Walsh and O’Flaherty say O’Donovan is getting no special privileges, but e-mail traffic suggests administration officials have been accommodating — even chummy — toward O’Donovan, readily accepting meetings he proposes, and helping him network with other city employees who might be able to benefit him.

“Anything for an O’Donovan,’’ interim Public Works Commissioner Michael Dennehy wrote to O’Donovan in 2014.

People who work in Boston’s real estate and lobbying worlds say O’Donovan appeared as if from nowhere to become one of the new go-to guys for companies that need something from city government.

Before Walsh took over, there is little record of O’Donovan in City Hall e-mail traffic. He had no e-mail contact with the Boston Redevelopment Authority in the two years prior to Walsh talking office on Jan. 6, 2014, the agency said. City departments during those years included O’Donovan on just two impersonal “mass e-mails,’’ Walsh’s office said.

Since the start of the new administration, O’Donovan has exchanged 668 e-mails with city departments and the BRA, officials say, in response to Globe public records requests.

The perception that City Hall works better for the well-connected is as old as municipal government, and its drab concrete corridors remain fertile ground for lobbyists and lawyers with friends in high places. O’Donovan is just one very active example among the new faces leveraging influence in Boston’s seat of government.

During his 2013 mayoral campaign, Walsh promised a new era of transparency at City Hall, vowing in his inaugural address to “set tough, new ethics standards for my staff . . . [with] new rules against conflicts of interest.’’

Walsh, in an interview, defended his administration’s interactions with lobbyists, saying he has no favorite sons in the influence industry and has cast nobody into political Siberia — an accusation frequently lobbed against his predecessor, Thomas M. Menino.

“Certainly we don’t favor any one particular person or dislike anyone else,’’ he said. “With a change of administration — you’ve got to figure the [Menino] administration was here for 20 years — people got used to going to the same people over and over and over to get things done. Now there’s an opportunity for other people to get involved with the city.’’

O’Donovan is “doing business in the city of Boston,’’ Walsh said. “I don’t see a problem with that.’’

“I’m not going to tell [anyone] they can’t represent somebody because they have a relationship. That’s not fair. But they’re not going to get any special privileges from me.’’

O’Donovan, long a fixture in Somerville as a 13-year member of the Board of Aldermen, has opened a second office more befitting a Boston rainmaker, in a stately red-brick building at 10 Tremont St., a chip shot from City Hall Plaza. He did not respond to messages left by phone, e-mail, text, and in person at his offices.

O’Flaherty, the city’s corporation counsel, said in an e-mail that he has not helped O’Donovan’s business. “My personal friendships and relationships do not influence me or my professional work,’’ he said.

O’Donovan’s e-mails with the BRA have yet to be released to the Globe, but his e-mails with city departments show how O’Donovan used his connections to win friendly introductions to key city officials.

In May 2014, five months into the new administration, e-mails show, O’Donovan sought a favor from a friend — Stephen Passacantilli, then a special assistant to Walsh at City Hall, whom O’Donovan had known for many years. O’Donovan had also represented him in an unrelated 2011 court case.

O’Donovan wanted help pitching Bio-Organic Catalyst, a California cleaning product maker, to Dennehy, the public works commissioner, and to Henry F. Vitale, executive director of the Water and Sewer Commission.

In an e-mail to Passacantilli, O’Donovan described one of the company’s products and inquired: “Can I ask you to forward this to Mr. Denehy [sic] & Mr. Vitale.’’

Subsequent e-mails suggest that O’Donovan obtained an in-person meeting with top public works officials two days later.

Within a week, O’Donovan was writing Dennehy directly, and offering to drop off a free sample for the department to test.

“It sounds like a great product,’’ Dennehy wrote back. And in another e-mail: “Thanks Sean. We look forward to working with you.’’

Dennehy, in an e-mail to the Globe, said O’Donovan got no special treatment.

City purchasing records show that the Walsh administration has since spent about $7,100 on Bio-Organic Catalyst products.

With the public works department on board as a client, O’Donovan sought to expand sales within the city, the e-mails indicate.

In July 2014, Michael Brohel, deputy commissioner of public works, connected O’Donovan via e-mail with a city engineer to talk about cleaning products for use at Spectacle Island, a city-owned former landfill.

The next month, O’Donovan asked Brohel if he could meet with the Boston Fire Department about one of the company’s oil-spill cleaners. “Not sure I will have time to join you in a BFD meeting,’’ Brohel responded, “but let me see if I can find you a contact over there.’’

In October 2014, O’Donovan credited Dennehy and Brohel for indirectly helping him make a sale to a private transfer station operator. “Thank you again because of our relationship with you this became possible,’’ he wrote. In another e-mail he gushed: “Marty is lucky to have you lads!!’’

Parker Dale, chairman of Bio-Organic Catalyst, said O’Donovan has worked for the company as an independent sales representative for more than six years; O’Donovan’s recent financial disclosure forms as a Somerville office holder, covering 2011-13, show no income from the company.

“He’s good with people that deal with waste water,’’ Dale said of O’Donovan. “It’s very blue-collar. He’s not your typical lawyer. He doesn’t come across slick.’’

O’Donovan is skilled at “driving to have a meeting taken,’’ Dale said. “When you don’t know anybody, it makes a huge difference to have somebody who can organize and get you in front of the right people to hear your story.’’

The mayor’s office said O’Donovan’s lobbying has not led to any major city purchases. The city in September 2014 spent $109,906 on trash receptacles and software from BigBelly Solar, Inc., according to a city purchase order. The purchase came shortly after O’Donovan met with public works officials about the company, according to e-mail traffic reviewed by the Globe. The mayor’s office noted, however, that BigBelly is a well-established city vendor dating back to the Menino administration.

The city has not yet bought an asphalt patching product that O’Donovan pitched to public works, though two days before the Globe inquired last month, city officials and O’Donovan were discussing the product via e-mails.

The Boston Water and Sewer Commission in 2015 spent $17,875 on products from Bio-Organic Catalyst, the commission confirmed.

O’Donovan’s friendship with Passacantilli opened doors for O’Donovan’s legal business as well.

This past October, Passacantilli — by then director of operations in the transportation department — hooked up O’Donovan with Edward Hesford, supervising traffic engineer, to discuss a residential project proposed by a developer O’Donovan represented.

“Eddie,’’ Passacantilli wrote to Hesford, “I mentioned to you yesterday I needed some help connecting you and a friend of mine doing work in Beacon Hill . . . Sean is a great guy and friend. I would appreciate it if you could find time for him and help him out with some questions he has regarding the project.’’

Hesford responded five minutes later: “Glad to help.’’

Just this past Thursday, O’Donovan filed notice to the BRA for the project, a 75-unit condo development at 33-61 Temple St.

Walsh is OK with Passacantilli doing favors for a friend. “As long as Stephen doesn’t cross the line and doesn’t tell them to give him a case or give him a contract or give him something, I don’t see a problem with that,’’ the mayor said.

Passacantilli, in an e-mail to the Globe, said: “I am willing to introduce anyone with the right person if they ask. An introduction is nothing more than an introduction.’’

With an apparent boost from O’Flaherty, O’Donovan also worked connections for his own family.

On March 27, 2014, the day after a Back Bay blaze killed two firefighters, O’Donovan wrote to Joyce Linehan, Walsh’s chief of policy, who spearheaded grass-roots organizing for the campaign of US Senator Elizabeth Warren. “I’m so sorry about yesterday’s tragedy!’’ O’Donovan began, before getting to the point: His nephew wanted a recommendation from Warren for an appointment to the US Naval Academy. O’Donovan suggested that O’Flaherty had steered him to Linehan: “In talking to Gene he thought I needed to speak with you directly.’’

Responded Linehan: “I spoke to Gene and am happy to make this call to the Senator.’’

Walsh said O’Donovan also asked him about the recommendation, and that the mayor asked Linehan to work on it. “There have been plenty of people coming to me over the years to ask if I can help them . . . trying to get an appointment letter,’’ Walsh said. “I’d do it for everyone who asked me.’’

Walsh acknowledged, however, that he has helped just this one applicant for a service academy recommendation since becoming mayor.

Walsh has met with O’Donovan twice since he took office; one time as a general catch-up talk, Walsh’s office said, and once to discuss a proposed condo tower at 171-172 Tremont St., whose developer O’Donovan represents.

The mayor confirmed that O’Donovan has hosted two political fund-raisers for him.

“A lot of people did fund-raisers for me,’’ Walsh said. “People who did business in the city of Boston for years, who were very close to the previous administration, did fund-raisers for me. So that’s no different.’’

The relationship between O’Donovan and O’Flaherty dates back at least to Malden Catholic High School, from which they both graduated in 1986, according to the school. Each earned a law degree from Massachusetts School of Law in Andover, which does not require applicants to take the LSAT for admission and is not accredited by the American Bar Association. Both men passed the bar exam.

O’Flaherty’s 1994 application for admission to the state bar includes a letter of recommendation from O’Donovan’s father, a lawyer.

“I have known this young man since childhood,’’ James A. O’Donovan wrote of O’Flaherty. “He is a friend and companion of my son, Sean, who himself was recently admitted to the bar.’’

The young lawyers joined forces in a law firm at 741 Broadway in Somerville. O’Flaherty worked at the firm while serving as state representative for Charlestown; he ascended in 2002 to the chairmanship of the influential Judiciary Committee.

In 2008, while O’Flaherty was Judiciary chairman, O’Donovan’s wife, Peri S. Nawawi, was hired as an assistant magistrate in Charlestown District Court, which was in O’Flaherty’s legislative district. She still holds the position, earning $103,000 annually.

Some assistant magistrate hires have been linked to patronage in the past, but O’Flaherty and Charlestown’s clerk-magistrate, John Whelan, both said O’Flaherty had nothing to do with the hiring.

Whelan said a three-member interview panel named Nawawi a finalist. “She’s really good at this. If I had to do it over again, I would do the same thing,’’ said Whelan, who was an O’Flaherty campaign donor, as was Nawawi. “I feel bad that she’s going to be cast as a hack or something like that. It’s lousy.’’

Walsh backed up O’Flaherty’s insistence that he has not pulled strings for O’Donovan. “Gene’s not the mayor of Boston,’’ Walsh said. “Gene doesn’t get involved in development. Gene doesn’t get involved in licensing stuff.’’

O’Flaherty, however, does help make connections.

Last September, the mayor’s deputy chief of staff wrote to O’Donovan: “My favorite person in City Hall :) gave me your contact information and asked me to reach out regarding a meeting request you have for Mayor Walsh,’’ she wrote.

Who was that person who moved along O’Donovan’s request? It was O’Flaherty, the mayor’s office confirmed.

Mark Arsenault can be reached at mark.arsenault@globe.com. Andrew Ryan can be reached at andrew.ryan@globe.com.