Miller becomes the Canadian franchise's third designated player after signing an undisclosed contract, subject to international clearance.
"I'm delighted to be making this move to Major League Soccer and Vancouver Whitecaps FC," Miller told his new club's website.
"I have heard many great things about the club and the city of Vancouver, and have been impressed by the standard of MLS.
"To have the chance to continue my career in North America with Whitecaps FC is a fantastic opportunity for me and my family."
The former Rangers and Celtic frontman, 32, made 49 appearances for the npower Championship side last season and scored 11 goals.
He has also featured in the Barclays Premier League for Wolves and Derby and scored 16 goals in 60 international caps.
Whitecaps head coach Martin Rennie said: "We're delighted to bring an experienced striker like Kenny to our club.
"He has been a proven goalscorer with big clubs in Scotland and played in the England Premier League. His speed, energy, and work rate will be a valuable asset to our club as we look to have a strong second half of the season in MLS."