Watkins will miss the rest of the campaign due to the knee injury he suffered against Castleford Tigers two days ago.
The centre underwent a scan on Monday morning which diagnosed damage to an anterior cruciate ligament (acl). He will undergo surgery and is expected to be sidelined for around eight months.
Rhinos have recalled centre Jimmy Keinhorst from a loan spell at Widnes Vikings and he could step in against Catalans Dragons on Saturday.
“It is just one of those things,” said Watkins. “I am devastated, but at the same time I have got to go and support the team as best I can off the field.
“It is pretty hard to take, but I have been through it before and I will certainly do my best to get myself right.”
Watkins suffered a similar injury to his other knee earlier in his career.
He will undergo surgery and could be available for the start of the 2019 season if all goes well.
The injury is a blow to Leeds, who have lost their skipper, goal kicker and most potent attacking weapon.
It will also rule him out of England’s four Tests against New Zealand this year.