Sejdić was born in Berlin, Germany to Bosnian parents. His father hails from Jakeš near Modriča and his mother hails from Derventa. They fled Bosnia due to the Bosnian War and took refuge in Germany.[2] At age four, Sejdić moved to the United States.[3]
Sejdić began his youth career with the U-15 team for the Derby City Rovers in Louisville, Kentucky. After three years with the Rovers he moved abroad to play in the youth academy of Vitesse in the Dutch Eredivisie. Sejdić played a single season with the U-16 team of Vitesse before coming back to the United States to play with the U-17 and U-18 academy teams of Real Salt Lake. Upon graduating high school, Sejdić signed a National Letter of Intent to play college soccer at the University of Maryland, College Park.[4]
Ahead of the 2015 NCAA Division I men's soccer season, Sejdić was ranked number 50 by TopDrawerSoccer.com in his graduating class and number 37 by College Soccer News in his graduating class.[5] Of incoming first year students, he was ranked 10th by TopDrawer Soccer[citation needed] and during the year he became a regular rotation player, appearing in 15 matches for the Terrapins.[citation needed] Sejdić scored his first two college goals against St. John's on August 30, 2015. On September 27, 2015; Sejdić notched his first collegiate assist in a 4–1 win against Wisconsin.[citation needed]
During his second year he appeared in all matches for the Terrapins, where he contributed to nine goals and nine assists during the 2016 NCAA Division I men's soccer season.[6] Two of Sejdić's nine goals came during the 2016 NCAA Division I Men's Soccer Tournament, in a 4–5 loss to Providence.[7] During the 2017 season, Sejdić remained an integral part of the team and scored three goals and dished out four assists.[8]
Sejdić had a breakout season during 2018, as he was named to the Big Ten best XI during the 2018 Big Ten Conference men's soccer season.[9] Sejdić helped lead Maryland to their fourth College Cup title,[10] earning offensive MVP honors.[11][12]
Senior
During the 2017 and 2018 PDL seasons, Sejdić played for Derby City Rovers.[13]
On 7 July 2021, Sejdić was traded to Atlanta United in exchange for $100,000 of General Allocation Money, with the potential for the fee to rise another $50,000.[15]
On 8 February 2024, Sejdić signed with Nashville SC on a one-year deal following a successful preseason trial with the club.[16] He was released by Nashville following their 2024 season.[17]