Rhinos captain Watkins has been given the all-clear to play for the first time since suffering an anterior cruciate ligament injury against Tigers at the Magic Weekend last July.
Marquee signings Konrad Hurrell and Trent Merrin are set to make their first appearance for Leeds and Brett Ferres is included after recovering from surgery on a wrist.
Wingers Tom and Luke Briscoe both miss out due to minor injuries, but are expected to be available for Rhinos’ Betfred Super League opener at Warrington Wolves on Saturday, February 2.
Forwards Carl Ablett and Dom Crosby are still recovering from surgery.
Utility-back Jordan Rankin will play his first game for Tigers following his move from Huddersfield Giants last week.
Super League young player of the year Jake Trueman will make his comeback from the wrist injury he suffered at the end of last season and Cory Aston has an opportunity to impress against his former club.
Leeds Rhinos: from Walker, Watkins, Hurrell, Handley, Lolohea, Myler, Cuthbertson, Parcell, Singleton, Merrin, Ward, Dwyer, L Sutcliffe, Ferres, Peteru, Oledzki, Jones-Buchanan, Smith, Donaldson, Newman.
Castleford Tigers: from Aston, Clare, Clark, Cook, Eden, Foster, Massey, Mata’utia, McMeeken, McShane, Millington, Milner, Minikin, Moors, Rankin, Sene-Lefao, Shenton, Trueman, Turner, Watts.