Rhinos were presented with the Women’s Super League leaders’ shield after a 50-6 win at York City Knights.
They were already the Challenge Cup holders and are hoping to complete a treble in this month’s Grand Final.
Rhinos finished a point clear of second-placed Wigan Warriors after losing only two of their 12 league matches.
Coach Adam Cuthbertson’s side will play host to fourth-placed Castleford Tigers in a semi-final this weekend and the winners of that will face either Wigan or St Helens in Manchester on Saturday, October 13.
Rhinos ran in nine tries against bottom of the table York, Courtney Hill converting seven of them after missing with her first two attempts.
Centre Sophie Robinson crossed twice in the first half and completed her hat-trick with the game’s final try.
York put up strong reistance for the opening 15 minutes, but Leeds hit their stride after Robinson’s opener. Suze Hill crossed and Hanna Butcher, Rhiannion Marshall and Caitlin Beevers all scored solo tries to open a 32-0 interval lead.
Beth Lockwood went over a minute after the break, but the second period was more even and Rhinos added only two more tries, through Ellie Oldroyd and Robinson’s third touchdown.