Flames reached the final courtesy of a 4-1 victory against Peterborough Phantoms, while MK Lightning went through after a 2-1 shoot-out success against Basingstoke Bison.
Goals by Kevin Phillips, Matic Kralj and Janis Ozolins put Flames 3-0 ahead by the 30-minute mark in the final, but Frantisek Bakrlik fired home late in the second period to give Lightning hope.
Danny Meyers made it 4-1 midway through the third, before Lewis Cook brought Pete Russell’s team to within two after 53 minutes.
Andrew Hemmings quickly restored Flames’ three goal advantage, with Ben Campbell’s goal with four minutes left sealing a deserved 6-2 victory.
Saturday – play-off semi-finals
Basingstoke Bison 1-2 MK Lightning 2 (SO)
Peterborough Phantoms 1-4 Guildford Flames
Sunday – play-off final
Guildford Flames 6-2 MK Lightning