Often described as "the gold standard" for fiscal conservatism in Congress, the National Taxpayers Union rated him the best vote for taxpayers in the House four times, most recently in 2020. Citizens Against Government Waste recently named him as one of the perfect votes in the House fighting wasteful government spending.

McClintock is a member of the House Judiciary Committee where he serves as Chairman of the Subcommittee on Immigration Integrity, Security, and Enforcement and also serves on the Subcommittee on the Constitution and Limited Government. He is a senior member of the House Natural Resources Committee where he serves on the Subcommittee on Federal Lands, which he chaired from 2015 to 2018, and on the Subcommittee on Water, Wildlife, and Fisheries, which he chaired from 2011 to 2015. The Congressman is also a member of the House Budget Committee and has proposed major fiscal reforms to curb unauthorized appropriations, control mandatory spending, balance the budget and protect the nation's credit.

Prior to his election to Congress, McClintock served 22 years in the California legislature, where he became one of its most recognized conservative leaders. He twice received the Republican nomination for State Controller, narrowly missing election in 2002 by 23/100ths of one percent. He ran as the conservative standard bearer for Governor in California's historic recall election in 2003.