Jol described Rodallega's arrival as a "massive boost" ahead of the new campaign.
Fulham's strike options have been weakened over the summer following the departure of Andy Johnson while Pavel Pogrebnyak, who impressed on loan in the second half of last season, opted to join newly-promoted Reading.
"I am delighted that Hugo has decided to join Fulham," Jol said.
"There has been a lot of interest in him from other top flight teams in England and abroad, so to be able to add his quality to our squad is a massive boost this early in our preparations for the new campaign.
"He is a great addition and I think he will contribute very well to our style and philosophy here."