The Frenchman had looked to be on his way to a comfortable win over sixth seed Marcel Granollers in his semi-final as he took the opening set 6-2.
But the Spaniard hit back in the second set, which he won 6-4 to force a decider.
Roger-Vasselin held his nerve to battle back from conceding an early break in the third set to round out a 6-2 4-6 6-3 win and advance to just his second final.
"Hopefully, I can win one more match," he told www.atpworldtour.com
"It is a great start to 2014. I hit a lot of winners in the first set, but he played better in the second. I didn't lose my concentration. I stayed calm and I was able to change the match in my favour, from a 0-2 deficit, in the decider."
Top seed Wawrinka was being given a difficult time by Canada's Vasek Pospisil in his last-four clash, but was handed victory when his opponent was forced to retire.
The Swiss had taken the first set 6-4 and the second was tied at 5-all when Pospisil had to withdraw.