Rhinos led only 4-0 with 14 minutes left, but a try by impressive prop Zoe Hornby opened the floodgates and Leeds ran in three more to keep alive their faint hopes of a home semi-final.
The victory lifted Rhinos to second in the table but St Helens will finish as runners-up to champions York Valkyrie if they beat Warrington Wolves on Sunday. Second will host third in the play-offs, with fourth-placed Wigan travelling to York.
Rhinos dominated the first half, but managed only one try, through a powerful finish by Amy Hardcastle on 35 minutes.
Wigan got into Leeds’ 20 just once in the opening period and it was a similar story after half-time as Rhinos continued to apply pressure, only to be thwarted by the visitors’ outstanding defence.
Rhinos captain Hanna Butcher was held up over the line and Sophie Robinson and Sam Hulme both went close before Hornby dabbed a kick between the posts and followed up to touchdown.
That try, converted by Hulme, finally ended Wigan’s resistance. Caitlin Casey scored off her own kick in the next set; Hornby forced her way over from close-range, Hulme converting and Hardcastle’s second try completed the scoring with seven minutes left.
Leeds Rhinos women: Nuttall, Hulme, Hardcastle, Robinson, Gaines, Casey, Butcher, Hornby, Bennett, Northrop, Murray, Frain, Dainton. Subs Greening, Sykes, Lockwood, Glynn.
Wigan Warriors women: Salihi, Greenfield, Davies, Hunter, Hilton, Banks, Marsh, Speakman, Harborrow, Johnson, Molyneux, Coleman, Doria. Subs Hayes, C Jones, Morris, M Jones.
Referee: Matty Clayton.