The couple, who have been dating since 2005, had a small private wedding near their home in Malibu before jetting off to Las Vegas for a mini honeymoon.
The source told the National Enquirer magazine: "The vows basically said that they would 'be forever in love' with one another and that they would always be together. For the two of them, it was as good as a marriage ceremony."
Jim had previously claimed that proposing to Jenny would "ruin" their relationship, but it looks like he finally had a change of heart.
A source added: "He insists that he and Jenny are incredibly happy together, and they don't want to jinx things by tying the knot. Jim says he doesn't need a legal ceremony or a piece of paper, and Jenny feels the same."
They make such a great couple, they're always smiling and laughing and seem like they're genuinely in love, and so we couldn't be happier for them. Congrats to the couple!