Who was the son of Krishna and Rukmini?

The son of Krishna and Rukmini was Pradyumna.

Pradyumna is described in Hindu tradition as Krishna’s eldest son by Rukmini, Krishna’s chief queen. He is especially prominent in the Bhagavata Purana, Harivamsa, and related Vaishnava traditions. The Mahabharata also identifies him as a celebrated Vrishni hero and associates him with Sanat Kumara.

His birth story is unusually dramatic. The demon Shambara abducted the infant Pradyumna after learning that the child would eventually destroy him, throwing him into the sea. A fish swallowed the baby, but fishermen later caught it and discovered him alive. Pradyumna was raised by Mayavati, who helped him learn the magical knowledge needed to defeat Shambara.

A common mix-up is with Aniruddha: Aniruddha was Pradyumna’s son and therefore Krishna’s grandson. Samba was another son of Krishna, traditionally associated with Jambavati, while Bhanu appears among Krishna’s other descendants. Pradyumna later fathered Aniruddha with Rukmavati, linking him to the next generation of the Yadu dynasty.