Jon Gosselin Marries Stephanie Lebo in Intimate Ceremony

Jon Gosselin is giving marriage another shot ... tying the knot with his longtime girlfriend Stephanie Lebo in an intimate Pennsylvania ceremony -- with some of his kids there for the big moment.

Sources with direct knowledge tell TMZ ... the couple exchanged vows in a low-key ceremony at The Barn at Silverstone in Lancaster, PA -- surrounded by 180 loved ones.

Two of Jon's eight children he shares with ex-wife Kate Gosselin -- Hannah and Collin, who are now 21 -- were in attendance. Collin stood right by his father's side, serving as one of the groomsmen.

Stephanie's daughter, Juliana, was also there.

In footage of the wedding captured by ET ... Jon was seen looking sharp in a gray suit, while Stephanie stunned in a beautiful ball gown. The pair shared a passionate kiss after the officiant said, "You may now kiss the bride," and the crowd erupted.

You'll recall ... Jon was famously married to Kate Gosselin from 1999 to 2008 ... with their marriage becoming the centerpiece of the hit reality show "Jon & Kate Plus 8." Things have been rocky between them in recent years ... as they split custody of their sextuplets and two other kids.

As for what's next ... we're told the newlyweds are planning a Caribbean cruise for their honeymoon next year.