LSU Director of Athletics Scott Woodward made the announcement Sunday, a day after coach Nikki Fargas stepped down.
"Kim Mulkey is a champion and a Hall of Famer, and we are thrilled to welcome her home," Woodward said in a statement. "Her accomplishments are unprecedented, her passion is unrivaled, and her commitment to winning in all aspects of life - in the classroom, on the court, and in the community - is unparalleled."
Mulkey led the Lady Bears to four Final Fours in her 21 years in Waco, winning three national titles. She also coached the 2012 Lady Bears in a perfect 40-0 season, the most wins in college basketball history.
Baylor appeared in 19 NCAA tournaments in 20 years during her tenure.
Mulkey returns to her home state, and will coach just 50 miles from where she grew up in Tickfaw, Louisiana, a town of around 760.
She went on to become an All-Americana point guard at Louisiana Tech, where she won two national championships before serving as an assistant coach for the Lady Techsters for 15 years.
She was inducted into the Basketball Hall of Fame in 2020 and the Women's Basketball Hall of Fame in 2000.
While her salary wasn't disclosed, Mulkey's salary at Baylor was more than $2 million, while outgoing LSU coach Fargas earned around $700,000, according to WBRZ-TV.
Mulkey becomes the eighth head coach in LSU women's basketball history.