Private Sector and Local Politics
Following his graduation, Funabashi began working for the construction company Hokuto Kensetsu. Rising the ranks of the company, he eventually became its president; a positition he held until 2014.
In 1991, Funabashi was elected to the city council of Kitami, serving for a singular term. At the end of this term in 1995, he successfully ran for Kitami's seat in the Hokkaido Legislative Assembly, where he would serve for five terms until 2012.
House of Representatives
Ahead of the 2012 Japanese general election, he was selected by the Liberal Democratic Party (LDP) to be the parties' candidate in Hokkaido 1st district in the House of Representatives. In this race, he successfully ran against incumbent Democratic Party of Japan (DPJ) representative Takahiro Yokomichi, who was at that point Speaker of the House. Yokomichi would lose his seat, but remain in the House of Representatives via the proportional representation system. After winning this race, Funabashi would become the first member of the LDP to represent Hokkaido's first district.
During the 2014 Japanese general election, Funabashi would seek reelection to the House of Representatives from Hokkaido's 1st district. He was defeated in the election by his previous opponent Takahiro Yokomichi, returning the seat to the DPJ. He garnered 105,918 votes, the most for an unelected candidate across the entire election. Despite the LDP winning three seats in the Hokkaido proportional representation block, Funabashi did not secure a seat via proportional representation; being the only unsuccessful first-past-the-post candidate in Hokkaido to not be elected proportionally.
Funabashi would run again in the 2017 Japanese general election, again in Hokkaido's first district. He lost the election to Daiki Michishita of the Constitutional Democratic Party. However, he would win a seat in the House of Representatives as part of Hokkaido's proportional representation block and return to national politics. Funabashi failed to be reelected in the 2021 Japanese general election, despite the LDP gaining a seat from the proportional representation district.
Senate
Funabashi would run in the 2022 Japanese Senate Election for the Hokkaido at-large district as an LDP candidate, winning one of three seats alongside fellow LDP member Gaku Hasegawa and CDP candidate Eri Tokunaga.
Later in October 2022, then-Prime Minister Fumio Kishida was embroiled in a nepotism controversy regarding the appointment of his son Shōtarō Kishida as a policy secretary. During the affair, it was brought to public attention that Funabashi had also similarly appointed his eldest son as a staffer to his role in the National Diet. Funabashi would address this controversy by stating that he had hired his son based on his son's interest in politics, rather than familial ties.
In August 2024, Manabu Horii, a member of the House of Representatives representing the Hokkaido proportional representation block, resigned from his seat due to a violation of fiscal electoral law. As a result, the Central Election Management Council selected Toshimitsu Funabashi to fill the vacancy; being that he was runner up for Horii's seat during the previous election. However, Funabashi declined to take the seat, citing a wish to remain a member of the Senate. Having failed to resign from the Senate, Funabashi officially forfeited the seat. As a result, the seat then passed on to former member of the House of Representatives and current member of the Hokkaido Legislative Assembly Kazuo Maeda; who also declined the seat. Ultimately, the seat was given to Yūsuke Takahashi, who had previously run in Hokkaido's 2nd district during the last election.
In September 2024, a leadership election for the Liberal Democratic Party was held. There were nine candidates in the running. A member of the Shikōkai faction, Funabashi endorsed fellow faction member and Minister for Digital Transformation Taro Kono. After Kono was eliminated in the first round, Funabashi alongside senior members of Shikōkai met in a hotel in Tokyo and decided to support ultraconservative Nara 2nd district representative Sanae Takaichi in the second round. The leader of the Shikōkai, Taro Aso also would later publicly endorse Takaichi. Later that day The Sankei Shimbun would report that Aso had privately instructed members of the Shikōkai faction to vote for Takaichi in the first round. Though Funabashi supported Kono in the first round, he did not publicly disclose who he voted for in the second round.
On 24 October, 2025; Funabashi became chair of the Fisheries Division of the Policy Research Council of the Liberal Democratic Party. Later on in 2026, Funabashi became chair of the Senate Committee on Agriculture, Forestry, and Fisheries.
