Goodwillie, who has scored 16 goals for the Terrors this season, had already won the Professional Footballers' Association young player award on the weekend and is now the SPL's best young player.
The 22-year old admitted he did not expect this award, as were his thoughts on the PFA prize, and said his focus at the moment was just to perform well for his club.
"It's been a great few days for me. I wasn't really expecting this so I'm just really happy and surprised," Goddwillie said.
"It's good that people are still noticing me playing well and that's the only thing I want to concentrate on right now."