Born in Zemun, Sekulić started his career playing in the youth team of local club FK Zemun. In 2009 he became senior and played on loan at Grafičar Beograd.[2] Next season he signed with Beograd.[3]
In the summer of 2011 he moved abroad to Slovakia and joined Košice at the age of 19. Sekulić was a stable player for Košice Reserves, making 13 appearances. On 3 March 2012, he made his debut for the first team, playing ninety minutes of a derby match, in a 1–0 away win against Tatran Prešov.[4]
On 15 February 2020, Sekulić moved to Major League Soccer side Chicago Fire on a three-year deal.[6] On 11 October 2020, he scored his first MLS goal against D.C. United at Soldier Field.[7] He left Chicago following the expiration of his contract at the end of the 2022 season.[8]
On 17 February 2023, Sekulić returned to Górnik Zabrze on an eighteen-month contract.[9] He left the club at the end of his contract on 30 June 2024.[10]
In August 2017, Sekulić obtained Slovak citizenship, making him eligible to represent Slovakia[12] and in March 2018 he was called up to the national team by his former coach at MFK Košice, Ján Kozák, for two fixtures at 2018 King's Cup. Although he was benched in the semi-final 2–1 win over UAE, he played the entire final game against Thailand (3–2 win) as a right-back.