District 20 includes parts of Kern, Tulare, Kings and Fresno counties.
Boudreaux is also the Tulare County Sheriff.
Fong and Boudreaux will compete for the full-term seat, which begins in 2025.
The seat was held by Kevin McCarthy, who resigned after being ousted as Speaker of the House.
In January, a judge ruled that Fong is allowed to run for both the 20th Congressional District and re-election in his current seat in the Assembly. Fong was also endorsed by former President Donald Trump to fill the seat.
A separate special election will be held on March 19 to fill the vacant seat until 2025.