After graduating from high school Simms received a scholarship to the University of Louisville. During his freshman year, he saw limited action, playing in two games and throwing four passes. Simms then left Louisville to attend El Camino College in Torrance, California. While at El Camino he led the team to its fourth consecutive league title and threw for over 2,000 yards in ten games.
Simms received playing time during the preseason against the Jacksonville Jaguars on August 17, 2013. He completed all five of his passes for 73 yards. Simms played the following week against the New York Giants completing 6 of his 10 pass attempts for 120 yards and a touchdown. On August 29, the final preseason contest, Simms started and played the entire game against the Philadelphia Eagles. He completed 33 of his 44 pass attempts for 285 yards.
Simms threw his first career touchdown pass to tight end Jeff Cumberland in a Week 11 14-37 loss to the Buffalo Bills. During Week 13 against the Miami Dolphins, Simms came in relief of starter Geno Smith in the third quarter; he completed 9 of his 18 passes for 79 yards with an interception and a lost fumble in the Jets' 3–23 loss. Simms appeared in 3 games of the 2013 season and finished the year with 156 passing yards.
Simms, an exclusive rights free agent, was re-signed by the Jets on January 13, 2014. He was released on August 30, 2014 during the team's final roster cuts and signed to the team's practice squad a day later. He was promoted to the active roster on November 1, 2014.
Simms signed a one-year contract to remain with the Jets on December 30, 2014. However, after the team drafted Bryce Petty and signed undrafted rookie Jake Heaps, Simms requested his release and was granted it on May 28, 2015.
The Buffalo Bills claimed Simms off waivers on May 29, 2015. Simms was not expected to compete in the three-way competition for the starting quarterback position (Tyrod Taylor, EJ Manuel and Matt Cassel) but was in the mix as a potential backup quarterback and was given the start for the Bills' final preseason game against the Detroit Lions on September 3. Late in that game, Simms, while trying to break a tackle, inadvertently threw the ball 20 yards backward, creating a loose-ball situation and setting the Lions up for the game-winning score. Simms was released the next day.
On September 7, 2015, Simms was signed to the Atlanta Falcons' practice squad. On September 3, 2016, he was waived by the Falcons as part of final roster cuts and was signed to their practice squad the next day.
On May 15, 2017, Simms re-signed with the Falcons.