The 2010 Olympic gold medalist partially tore a repaired ligament in her right knee. She hasn't competed since tearing ligaments in the knee and breaking a bone in her lower leg at the world championships last February.
Vonn, 29, took a full practice run on Wednesday and said she had no setbacks with her knee.
"I was definitely nervous in the starting gate yesterday," Vonn told the Associated Press. "It's so familiar, yet foreign, because I just haven't been racing, and I don't have that adrenaline. And so that feeling was different. But now that I got that first run done with, I feel much better."
"You kind of know if your body is ready or not, and I feel like mine's ready."
The four-time World Cup champion, who has a seven-race winning streak at Lake Louise, said it was important to have a clean run at full speed while having no problems with her knee afterward.
"It usually swells pretty soon after if there's trauma," Vonn told reporters on Thursday. "It definitely doesn't take very long to tell, to see if it's going to get swollen or not, but I just gave it the whole day and nothing happened, thankfully. So all positive signs.
"It was just a matter of, did I nail the line. That was the goal yesterday, to ski solid, but ski the line, ski my race line. And I did that."
Vonn said she hopes to enter another downhill competition on Saturday as well as a super-giant slalom race on Sunday.