The break-in, at Stevie Ward's home, happened some time between 7.15pm and 10pm yesterday (Tuesday).
Gold rings are presented to winners of the Super League following victory in the prestigious Grand Final.
Ward's 2017 Grand Final ring - collected by Rhinos players after beating Castleford Tigers at Old Trafford last year - was stolen during the burglary.
"I had to go through quite a bit to get that ring.
"For someone to just come in and take it without the slightest bit of regard - to be so morally low and do that - it's not nice."
He added: "That week was one of the most significant of my life.
"At the start of the week I was questioning whether I would play the game I love ever again and then to play 80 minutes at Old Trafford to win the trophy was incredible, that ring encapsulates all that for me.
"I hope someone can help return it to me."
The thieves also stole laptops, cameras, electrical equipment and other property from his home in the Headingley area.
Ward had been out having a meal during the evening at Weetwood Hall, near Lawnswood, when the burglars struck.
"The frame of my front door was broken and the internal door was ajar because it had been kicked in."
Ward's unique 2017 winners ring is one of only 20 rings produced for each final featuring the distinctive 'S' design and '2017' across the middle of it.
Anyone with information is asked to call police on 101.