The 56-year-old Australian darts icon booked his place by beating Raymond Smith 10-7 in the final at Nissan Arena in Brisbane.
The victory was a relief for Whitlock, who failed to make last year's tournament which ended a 15-year qualifying streak.
"It means the world to me," said Whitlock, the world number 56.
"This gets me into the World Championship now and that gives me a lifeline to do some other things as well."
He added: "Just getting back in the World Championship, that's a lot for me and this means the world just to have a chance to be a world champion again.
"I just want to cry, but I'm not going to."
Whitlock will discover his World Championship opponent on Monday, with the draw taking place at 16:30 GMT in London.