Major (retd) Muhammad Muaz was passing through Allama Iqbal Town this evening when the attackers hurled a grenade at his car.
He was taken to to Shaikh Zayed Hospital, police officials said.
Provincial Law Minister Rana Sanaullah said it was yet to be ascertained who was responsible for the attack.
Lahore police chief Muhammad Aslam Tareen will head a committee that will probe the attack, officials said.