Goals by Danilo Orsi and Klaidi Lolos in the first half earned the three points which were enough for Scott Lindsey’s team to finish seventh. They’ll play MK Dons in a two-legged play-off semi – and will be off to Wembley if they come through.
The home leg is on May 6, the away leg May 9.
Photographers James Boardman and Stephen Lawrence of Telephoto Images were there to capture the action and the great post-match scenes as fans invaded the pitch and the players and management came out into the stand to join in the fun.
See the best of their celebration and action pictures on this page and the ones linked – and be sure to get the Crawley Observer on Wednesday for all the action and reaction.
29. Crawley Town's Ronan Darcy celebrates on the pits with the fans
Crawley Town's Ronan Darcy celebrates on the pits with the fans:Action and celebrations from Crawley Town's win over Grimsby, which clinched their League Two play-off place Photo: James Boardman:James Boardman / Stephen Lawrence / Telephoto Images
30. Crawley Town fans celebrate on the pitch after the match
Crawley Town fans celebrate on the pitch after the match:Action and celebrations from Crawley Town's win over Grimsby, which clinched their League Two play-off place Photo: James Boardman:James Boardman / Stephen Lawrence / Telephoto Images
31. Crawley Town's Jay Williams , Crawley Town's Klaidi Lolos (Centre0 and Crawley Town's Will Wright celebrate getting in the play offs
Crawley Town's Jay Williams , Crawley Town's Klaidi Lolos (Centre0 and Crawley Town's Will Wright celebrate getting in the play offs:Crawley Town's players celebrate their play-off place Photo: James Boardman:James Boardman / Stephen Lawrence / Telephoto Images
32. Crawley Town's Klaidi Lolos celebrates
Crawley Town's Klaidi Lolos celebrates:Crawley Town's players celebrate their play-off place Photo: James Boardman:James Boardman / Stephen Lawrence / Telephoto Images