The pair entered the competition as the world champions but had to settle for second spot on the podium after coming in 0.86s behind Slovakia's Henrieta Farkasova and guide Natalia Subrtova, the defending Paralympic champions.
The result marks a profitable first day of action for ParalympicsGB, who have been set an ambitious target of between six and 12 medals by UK Sport.
"I can't stop smiling. It is the best feeling in the world," Knight told BBC Sport afterwards.
"I was quite nervous at the start gate but once we pushed out, it was purely about doing what we had to do and thinking about the technical aspects down the course."
Knight and Wild will compete together again on Sunday in the Super G.