The American, whose comeback was interrupted by a training crash last month, said on her Facebook account on Thursday it felt great to be back on the Alpine ski circuit.
"After some good training at home in Vail and a solid downhill training run yesterday, I've decided to take today as a "rest day" but I will be racing tomorrow. I can't wait for my first race," she wrote.
Vonn has won 14 World Cup races in the Alberta resort and clocked the 19th fastest time in Wednesday's first practice session, 2.13 seconds behind Spain's Carolina Ruiz-Castillo.
"I love Lake Louise, I'm so confident on this hill. It was the perfect place for me to come back," said Vonn, who tore ligaments in her right knee at the February world championships in Schladming, Austria.
She partially tore her anterior cruciate ligament (ACL) and suffered a mild strain to the same knee in downhill training at Copper Mountain in preparation for last weekend's races at Beaver Creek, Colorado, that she missed.
"Of course I would have liked to come back for Beaver Creek but it just didn't work out. Hopefully this weekend will be good," she told journalists after the first practice at Lake Louise.
"I was a little bit nervous because it was my first time in a race situation since February so it's been a long time and I'm really happy.
"The knee feels good, it feels stable," she added.
The girlfriend of 14-times major golf champion Tiger Woods, Vonn insisted several times this season that she would be back on time to defend her Olympic downhill title in Sochi in February.
The four times overall World Cup winner is three wins short of the record of World Cup victories held by Austria's Marie Moser-Proell, a mark she could beat if she made it back to her best level this winter.