Williams' last game came for the Blues against Edinburgh in front of a total of just 3,580 and Warburton says that's no way for the 36-year-old to bow out.
Just 12 months ago Williams was appearing for the Barbarians against Wales in a 31-28 victory while his last appearance for Wales in the 2010 RBS 6 Nations came against Ireland.
Since then his place in the squad has been usurped by Warburton and Justin Tupuric but the skipper wants Williams to have a fitting send off.
"I was disappointed, to be honest, with the last game at the Blues when there was only about 3,000 there," he said.
"And for a player like Martyn, you think he deserves a better send-off.
"[It's] brilliant for him, yeah. He does really deserve that 100th cap and it would have haunted him for the rest of his life," said Warburton.
"He might not admit that, but I think he'd desperately want it. So I'm really chuffed for him that he's got that [coming]."