The 31-year-old ended speculation over his future by agreeing a new two-year contract earlier this week following months of negotiations.
Hangeland would have been eligible to leave Craven Cottage on a free transfer at the end of the season, but Jol is delighted he has committed until the summer of 2015.
Jol said: "We are ever so satisfied that he signed his contract because you never know. It was quite challenging trying to keep him.
"It was quite exciting because I thought I could lose him. He was a tower of
strength this year, last year and before I came here.
"He was on a free at the end of the year. It took a long time. We did everything and in the end it was a happy ending for us. He came in to sign it on Thursday and it was a relief.
"I don't think it is extraordinary that a player like Hangeland wants to stay here. All the players want to play here in London for Fulham.
"He can be grateful and we are happy he is staying. He is a very good player, one of the best players in the division in his position."