Born in Zagreb to Herzegovinian Croat parents and raised in Drinovci,[1] Majstorović started his career at the nearby NK Vinjani before moving to the nearby second-tier side NK Imotski's academy.
He made his debut in the Druga HNL at age 17, establishing himself as a starter in the club's defense in the spring part of the season.
The 2014/15 season saw the young centre-back join RNK Split's first-team squad, as the team's fourth choice on his position, behind Nino Galović, Tomislav Barbarić and Branko Vrgoč.
He made his Prva HNL debut on 7 November 2014, a day after his 21st birthday, in the 1–0 away loss to NK Slaven Belupo.
[2] Majstorović established himself, however, as the first team regular in the autumn part of the 2015/16 season, missing only a single game in the first 11 rounds, due to three yellow cards.