Born in 2366, Alexander is the son of Worf and the late Federation Ambassador K'Ehleyr.

Although Alexander spent his infancy with his mother, following her death he returned to Earth to live with Worf's adoptive parents, Sergey and Helena Rozhenko. Worf was initially reluctant to recognize Alexander as his son, fearing his discommendation would bring him shame.

As he grew older, Alexander resented the fact that Worf left him in the care of his adoptive grandparents. His disenchantment led him to enlist in the Klingon Defense Force, where he was assigned to the I.K.S. Rotarran. He served together with Worf aboard the Rotarran, but tensions with his father led to his eventual transfer to the I.K.S. Ya'Vang.

In 2374, Alexander agreed to take part in the wedding ceremony of his father and Jadzia Dax.