He was first elected to Cork City Council in 2004 and was an unsuccessful candidate at the 2007 general election for the Cork South-Central constituency, but was subsequently elected to the Seanad.[4] He was Fine Gael Seanad spokesperson on Community, Rural and Gaeltacht Affairs in the 23rd Seanad.
He was critical of the 2012 boundary commission report, which transferred the areas of Bishopstown and Glasheen from the Cork South–Central constituency to Cork North-Central. Both areas were considered his political base in the constituency.[5] Despite predictions that he would move to Cork North-Central at the next election, he announced in August 2012 that he would contest the next election in Cork South-Central.[6]
Following his involvement in the Oireachtas Golf Society scandal ("golfgate"), Buttimer resigned as Leas-Cathaoirleach on 21 August 2020. Buttimer and 80 others attended a golf function and dinner the previous day. At the time it was suggested it was in breach of government COVID-19 guidelines.[7] Buttimer's role in the matter was heavily criticised, as previously Buttimer has been highly critical of those he perceived as not keeping to government guidelines. In April 2020 he had accused broadcaster Ivan Yates of "irresponsible behaviour", telling him that public health measures were "about saving lives... not socialising". In June, he had suggested Donnchadh Ó Laoghaire was "happy to abandon public health advice".[8]
Buttimer also lost the party whip as part of his sanction. The party unanimously voted to restore the whip to Buttimer in January 2021.[9][8]
In April 2012, Buttimer came out as gay, the first Fine Gael TD to do so, saying: "I am a TD who just happens to be gay – it is just one little composition of the story that is me and I will continue to be the politician I was yesterday."[11] He married Conchobar Ó Laoghaire in December 2017.[12]