On June 18, 2022, Alaniz fought Tamara Elisabet DeMarco, for DeMarco's WBO world flyweight championship, in a fight that was televised to the Americas by TyC Sports' weekends boxing show, Boxeo de Primera. DeMarco had 10 wins and 4 losses in 14 professional contests before their fight. Alaniz, however, dominated the contest, dropping the champion twice in the first round and controlling the bout's pace until the champion's corner threw in their towel after the bell to start round seven had sounded, signifying that they were stopping the fight, and giving Alaniz her first world boxing championship by way of a seventh-round technical knockout. The fight was held in front of Alaniz' hometown fans at the Club Ferro Carril Oeste in Merlo.
