The 2008 United States Senate election in Montana was held on November 4, 2008. Incumbent Senator Max Baucus won re-election to a sixth term in a landslide, winning more than 70% of the vote and carrying every county in the state, despite Republican John McCain's narrow victory in the state in the concurrent presidential election. Baucus later resigned his seat on February 6, 2014 after the Senate confirmed him to be U.S. Ambassador to China, having already announced his intention to retire at the end of term on April 23, 2013. As of 2024, this is the last time Democrats won the Class 2 Senate seat in Montana.

Maxwell Sieben Baucus is an American politician who served as a United States senator from Montana from 1978 to 2014. A member of the Democratic Party, he was a U.S. senator for over 35 years, making him the longest-serving U.S. senator in Montana history. President Barack Obama appointed Baucus to replace Gary Locke as the 11th U.S. Ambassador to the People's Republic of China, a position he held from 2014 until 2017.