Born in Santa Rosa, California on March 13, 1992, Molly Hannis comes from an athletic background He father swam at Shippensburg University and brother Tyson swims at the University of the Pacific while her other brother, Cory is a diver at Santa Rosa Junior College.
As a high schooler, Hannis held five Santa Rosa records, including swimming the second-fastest high school 100y breast in the country in 2009. She was named a Swimming World Magazine five-star recruit, an was a seven-time NISCA high school All-American in the 100y breast and 200y IM events. Her 100Y Breast at the NCS Championships, 1:00.19, was the fourth-fastest in high school history.
At the 2008 US Olympic Trials, Hannis finished 23rd in the 100M Breaststroke.
College – University of Tennessee
SEC Championships, Hannis won the 100y breast title at the SEC Championships after swimming an NCAA automatic qualifying time of 59.60 seconds, and ended up 28th at NCAA Championships.
At the SEC Championships, Hannis set school records in both the 100 and 200 breaststroke, swimming in 58.22 in the 100 and 2:08.78 in the 200. She became first Lady Vol to swim under 2:10 in the 200 breaststroke and briefly held the SEC record in the event after the morning prelim session. She took silver in the 100 breaststroke.
At the NCAA Championships, Hannis placed ninth in 100 breast (58.84) and 13th in the 200 breast with time of 2:09.40.
At the SEC Championships, Hannis won her second straight silver medal in the 100 Breast, tying her own UT record and career-high in the process (58.22).
At the NCAA Championships, Hannis placed 6th in the 100 breaststroke, and 13th in the 200 breaststroke.
Hannis won silver in the 100 breaststroke for the third consecutive season, finishing in 59.01 seconds. She medaled in the event all four years of her career, taking gold as a freshman in Knoxville. She also took second in the 200 breaststroke, the first time medaling in her career in that event. She was part of the 4×50 Medley Relay and 4X100 Medley Relay that won gold.
At the 2014-2015 NCAA Championships, Hannis placed fifth in the 100 and sixth in the 200 Breaststroke.