Worf served aboard the USS Enterprise NCC-1701-D as a Lieutenant.  After the death of Lieutenant Tasha Yar, Worf became the Chief of Security and Tactical Officer.  After the destruction of the USS Enterprise-D (Star Trek 7: Generations), Worf was assigned to Deep Space Nine by special request of Captain Benjamin Sisko, who needed Worf to assist him in solving a problem with Klingons ("The Way of the Warrior, part 1 and 2" DS9).  After his assignment, Worf contemplated leaving Starfleet because he no longer felt welcome in the Federation and the Klingon empire no longer respected him or his house.  Captain Sisko talked Worf out of leaving and Worf became a permanent member of the Deep Space Nine crew.  Shortly after, Worf, who lost his house, joined the house of Martok.
    After being assigned to Deep Space Nine, Commander Worf fell in love with Commander Jadzia Dax.  Later, the two married.  When Jadzia Dax died ("Tears of the Prophets" DS9), Worf joined General Martok on a very dangerous mission to destroy a Dominion ship yard, it was the only why he felt he would be able to get Jadzia in to sto-vo-kor ("Image in the Sand" and "Shadows and Symbols" DS9).