The Belgian international striker was released by Man City in July making him a free agent which allowed him to sign after the window closed.
Plymouth boss Paul Sturrock said: "He is an international striker and they don't exactly fall off trees.
"He brings experience to the front line and gives us something different to what we have had before."
Sturrock added: "He is a big, strong boy and he has done it, seen it and got the t-shirt.
"He played in the Premiership 25 times last year and we are delighted to have that kind of standard here."