Fred Rutten's team dominated the vast majority of the opening Eredivisie fixture of the weekend at De Kuip - even before the visitors had Joey van den Berg sent off on the hour mark.
Yet a frustrated Feyenoord required a 70th-minute leveller from captain Immers to earn a draw after Hakim Ziyech put the 10 men ahead with a wonderful free-kick shortly after Van den Berg's dismissal.
That jolted the hosts into life, though, and Rutten's side soon began to control proceedings.
Mitchell te Vrede had Feyenoord's best chance of the first half when his header was well saved by Heerenveen keeper Kristoffer Nordfeldt shortly before the interval.
Despite that setback, Heerenveen went ahead soon after courtesy of Ziyech's 25-yard set-piece.
However, their lead lasted just three minutes, as Immers climbed highest to convert substitute Ruben Schaken's right-wing cross.
Feyenoord, who announced the loan signing of Bursaspor's Colin Kazim-Richards earlier on Friday, pressed for a winner with Elvis Manu and Tonny Vilhena going closest.
