[3] Heimer started playing football at Frederiksberg Boldklub [da], better known as FB, before joining KB for a short period and later B.93 at the age of 14.
[5] After over 70 first team games for B.93, Heimer left the club to join Thisted FC in January 2018.
After a year at Danish 1st Division club Thisted FC, Silkeborg IF announced on 30 January 2019, that Heimer had joined the club on a contract for the rest of the season.
[6] After leaving Silkeborg IF in December 2019,[7] Heimer signed with Næstved BK on 22 January 2020 on a free agent.
[8] Heimer confirmed on 26 July 2020, that his contract with Næstved had been terminated.