On 3–5 June, Mamun won the all-around gold at the 2016 Guadalajara World Cup with a total score of 76.550 points, in the apparatus finals: she also won gold in hoop, clubs, ribbon and placed 4th in ball. On 17–19 June, Mamun competed at the 2016 European Championships, she dropped her hoop once however she scored well in her remaining apparatus in ball(19.166), ribbon(19.133) and Clubs(19.333) - a European record under the 20 point CoP judging system; her overall results were enough to win her the all-around silver medal ahead of Ukraine's Ganna Rizatdinova.