Adams became a cheerleader for the apartment-sharing website in 2015 after lobbyist James Capalino and his staff met with him and his staff, according to lobbying records.
The borough president even lauded the tech firm in a June 4, 2015, keynote address he gave at the Steven L. Newman Real Estate Institute's "Building Brooklyn" conference.
"Brooklyn has a welcome mat for all the new, disruptive technologies,” Adams said in his speech. "I want Airbnb. I want Bitcoin. I want a marijuana dispensary. Come to Brooklyn."
Capalino's lobbying firm later posted Politico New York's story about Adams' speech to its Facebook account.
"They buy a lot of partnerships," said one group opposed to Airbnb that asked not to be named. "It's like having an elected official cheerlead for them."
Brooklyn's most prominent politicians, including Public Advocate Letitia James and councilmembers Jumaane Williams, Brad Lander and Carlos Menchaca, have all publicly opposed Airbnb because of its negative effect on affordable housing.
A 2015 report from New York Communities for Change and Real Affordability for All found that Brooklyn has eight of the city's top 20 neighborhoods for Airbnb.
While the city's average rent increased 32 percent from 2002 to 2014, the average increase in the top Brooklyn Airbnb neighborhoods was 45 percent.
Adams' praise came at a time when Airbnb had already been investigated by state Attorney General Eric Schneiderman and was facing scrutiny from local elected officials about the service's users skirting rental laws and occupancy taxes.
Airbnb, which paid $150,000 to Capalino's firm in 2015 to lobby Adams and City Council members, also made a hefty donation to the Brooklyn borough president's nonprofit, the One Brooklyn Fund, according to disclosures made to the city's Conflicts of Interest Board.
Adams met personally five times with Capalino's firm and two of those meetings were about Airbnb and had Airbnb representatives present, according to the borough president's office. Adams' staff met with Capalino's firm an additional time regarding Airbnb.
For comparison, Mayor Bill de Blasio met with Capalino twice since taking office.
Adams' staff said he requested the initial meeting on Dec. 9, 2014 and had a subsequent meeting on April 15, 2015.
Airbnb gave One Brooklyn's general fund a check for $32,000 on Aug. 20, 2015.
A spokeswoman for Capalino did not immediately respond to a request for comment.
Other topics that Capalino's firm lobbied Adams' staff on include for-hire vehicles, zoning and manufacturing, citywide ferry service, helicopter tourism, Brooklyn Bridge Park, NYCHA and land use.
Stefan Ringel, a spokesman for Adams, denied that the borough president's office had business dealings with Airbnb.
Ringel said Adams requested a meeting with the tech firm "to learn more about their business, including discussing his concerns with any potential violation of affordable housing regulations."
"Borough President Adams is a staunch supporter of the sharing economy and disruptive technology, and he has appreciated an ongoing and productive conversation with Airbnb," Ringel said.
Tom Cayler of the West Side Neighborhood Alliance, which opposes Airbnb, said he was disappointed to hear about its donation to the Brooklyn Borough President's office.
"I'm shocked that as the borough president of Brooklyn that his first concern and commitment isn't to affordable housing for his constituents," Cayler said.
"It's very clear to anyone dealing with housing issues that illegal hotels remove valuable housing stock from the market."
One Brooklyn has received more than $900,000 in donations from more than 30 donors since it formed in 2014. Adams’ office said One Brooklyn was set up to solicit donations to pay for things such as his “International Day of Friendship" and his New Year's Eve "ball drop" in Coney Island.
Ringel said the Airbnb donation was to One Brooklyn's general fund but was used to help pay for the New Year's Eve event.
An advisory letter Adams' office obtained from the Conflicts of Interest Board said that he and his staff must make it clear that the One Brooklyn donor "will receive no special access to the Borough President or to the Office or preferential treatment as a result of the donation."
Ringel said the borough president "believes strongly in the importance of corporate citizenship and he expects the business community to support non-profits, such as One Brooklyn Fund, Inc., to be an active part of addressing critical social challenges” and "to strengthen the important community-building work that helps the borough be a safer place to raise healthy children and families.”
Good government groups said One Brooklyn has similarities with the Campaign for One New York, the nonprofit formed by de Blasio to push his political agenda.
"They raise money from people who do business with the city and the borough, which is a problem," said Dick Dadey, executive director of Citizens Union.
"It's also being used as a platform for greater promotion of the association of the borough president with making borough activities happen."
Federal authorities are currently probing whether donors to the mayor's nonprofit received anything in return for their donation.
City records show Capalino has raised about $45,000 for de Blasio's re-election campaign. Capalino's firm also donated $10,000 to the Campaign for One New York.
Other One Brooklyn donors were Brooklyn developer Two Trees Management's philanthropic arm the Walentas Foundation and film production firm Broadway Stages, which has drawn scrutiny over its donations to de Blasio's campaigns.