Saturday's fixtures saw Vitesse, Ajax and Twente all win, meaning the pressure was on Feyenoord to pick up a result.
Nineteen-year-old winger Jean-Paul Boetius opened the scoring in the ninth minute as he chipped the ball over Kristoffer Nordfeldt in the opposing goal.
Lex Immers doubled Feyenoord's lead seven minutes later with a powerful low shot from just inside the area and, although Sven van Beek scored an own goal in first-half injury time, Heerenveen were unable to draw level.
Groningen failed to join Feyenoord on 27 points as ADO Den Haag claimed a 2-1 win at Euroborg.
Michiel Kramer's 32nd-minute strike looked set to decide proceedings in Den Haag's favour, only for Johan Kappelhof to equalise with 11 minutes remaining.
The visitors were not done, however, and struck again four minutes later through Tom Beugelsdijk to steal victory and climb out of the relegation play-off places.
PEC Zwolle are without a win in six league matches after being thumped 4-1 by Go Ahead Eagles.
Doke Schmidt and Erik Falkenburg struck in the first 15 minutes to put Go Ahead 2-0 up, with goals from Jarchinio Antonia and Jop van der Linden, the latter's from the penalty spot, making sure of the win in the second half.
Stefan Nijland pulled one back with 16 minutes left to play, but it was nothing more than a consolation as Go Ahead opened up a four-point gap between themselves and the bottom three.
Heracles completed their fourth Eredivisie away win of the season at Roda in Sunday's final match.
Wiljan Pluim gave hosts Roda an 18th-minute lead, but Heracles levelled just after the half-hour mark through Simon Cziommer.
An Oussama Tannane double in the last 11 minutes completed a fine turnaround for Jan de Jonge's men.
