Bristol-born Kersey-Brown grew up in Penmaenmawr and was a Wales schoolboy rugby union international.
He spent five years at London Welsh before switching codes to turn professional with Huddersfield in November 1967.
Kersey-Brown, who also played for Oldham, won two caps for Wales in the 1968-69 season.
"We're really sorry to hear that Alex has lost his long battle with cancer," Wales Rugby League's chairman Brian Juliff said.
"On behalf of everyone at Wales Rugby League, I would like to send our condolences to Alex's family and friends at this sad time."
Former Wales rugby league international Alex Kersey-Brown has died, aged 73, after a long battle with illness.