Dennis competed at the 2010 Covergirl Classic in the 10-11 Hopes Division, where she placed second.[1] In 2011 Dennis qualified to Junior International Elite status. She qualified to the Covergirl Classic in the Junior division. She finished 21st of 36 participants, with a score of 50.450[2] and therefore did not advance to the National Championships.
Dennis was scheduled to compete at the 2012 Secret U.S. Classic but withdrew due to injury.[3] She advanced to the 2012 National Championships as she had already qualified. She had an excellent two days of competition, accumulating a two-day all-around score of 109.550.[4]
Junior elite
2013
Dennis returned to the Secret U.S. Classic in 2013. She finished fifth all-around, picking up a gold medal in vault (15.250) and a silver on floor exercise (14.600).[5] Dennis advanced to the 2013 National Championships in Hartford, Connecticut. She finished her two days of competition with 112.550, placing fourth in the all-around.[6] She took home a silver medal on vault also.
2014
Dennis made her international debut in March 2014 at the City of Jesolo Trophy in Jesolo, Italy. She took home a team gold and individual silvers on the uneven bars and the all-around.[7] She went on to compete at the 2014 Pacific Rim Gymnastics Championships in Richmond, British Columbia, where she won the gold medal with the U.S. team and won silver in the all-around and on vault behind teammate Bailie Key.[8] In August Dennis competed at the U.S. Classic where she finished second in the all-around behind Jordan Chiles. She won gold on uneven bars, silver on vault behind Chiles, silver on balance beam behind Norah Flatley, and placed 26th on floor exercise.[9] Dennis finished the season competing at the National Championships. She placed second in the all-around behind Jazmyn Foberg. She placed first on vault and floor exercise, third on uneven bars behind Foberg and Flatley, 22nd on balance beam.[10]
Senior elite
2015
Dennis turned senior in 2015. On February 17, 2015, Dennis announced that she had committed to UCLA for NCAA gymnastics.[11] At the 2015 U.S. Classic Dennis did not compete on floor exercise. She finished sixth and seventh on uneven bars and balance beam respectively.[12] At the 2015 National Championships Dennis finished ninth in the all-around,[13] 13th on uneven bars, fourth on balance beam, and tenth on floor exercise.[14] Following the National Championships Dennis was named to the U.S. Senior National Team and was invited to the World Championships training camp.[15]