Mayes defeated former Palm Springs Police Chief Gary Jeandron in the primary and was elected to the State Assembly in November 2014, with 57.3% of the vote.

[8] Mayes was also appointed to the Select Committee on Renewable Energy Development and Restoration of the Salton Sea,[9] and was named Chief Republican Whip.

[15][16][17] Mayes was selected by his colleagues to serve as Assembly Republican Leader on September 1, 2015 succeeding Assemblywoman Kristin Olsen.

[20][21] As one of his first actions as Leader, Mayes took the entire Assembly Republican Caucus to visit St. John's Program for Real Change to meet with mothers who have emerged from abuse, poverty and homelessness.

[22] Later, Mayes negotiated with Governor Brown and legislative Democrats to craft a health plan tax package designed to draw down in more than a billion dollars in matching federal money.

In exchange for Republican support, Mayes secured language to provide more money to help people with autism and other developmental disabilities and forgiving a budget debt owed by skilled-nursing facilities.

[32] In January 2018, Mayes formed "New Way California," aiming to broaden the appeal of the Republican Party by advocating for "individual freedom, shared responsibility, educational excellence, environmental stewardship, efficient government and an open economy.

The summit featured several other Republicans from the State Assembly, including Rocky Chávez, Devon Mathis, and Jordan Cunningham.