Worf's biological parents were killed at Khitomer in a Romulan attack. His adopted parents, Sergei and Helena Rozhenko, human race, (from the planet Gault) were shown in "Family."

He has a brother (Kurn), a dead half-Human-half Klingon girlfriend K'Ehleyr, killed by Duras on stardate 44246 (in year 2367), a son Alexander ("Reunion", "Cost of Living", etc.), a bonded son Jeremy Astor ("The Bonding"), and a foster brother Simon from the Rozhenkos ("Heart of Glory").

Worf resided in deck 2, room 3118 on Enterprise-D. His current assignment is on Deep Space Nine station as a consultant when a war between Klingon and Federation started on stardate around 49000 ("DS9's Way of the Warrior"). On DS9 station, he prefers to reside on Defiant ship.

On Enterprise-D, he was involved with counselor Troi in a romantic relationship ("All Good Thing..."). It is believed that their love relationship was ended before he's assigned to DS9 station. However, on DS9 station, Worf is currently in love with Dax.

When the Borg invaded Earth on stardate 50893.5 (in year 2373) ("Star Trek: First Contact"), Worf commanded the Defiant to fight Borg. After the Defiant was heavily damaged but not destroyed, he joined Enterprise-E and her crew to go back to the past to save 2063's Earth from Borg's assimilation. After this mission, Worf went back to DS9 station.