The 50-year-old "Bajranji Bhaijaan" star became an uncle again when Arpita gave birth to her first son on March 30.
In the picture, which Salman posted on his social media sites, the actor is seen smiling at his nephew, who is fast asleep.
Arpita, who tied the knot with businessman Aayush in 2014, earlier took to Twitter to thank her friends and well-wishers for their love and congratulatory messages.
"Thank you for welcoming our Lil Prince with open arms and hearts filled with so much love and showering him with all your blessings and good wishes," she wrote.
"Our wait is over. Our little prince Ahil has arrived. Love Arpita and Aayush. P.S. Mother and son are doing fine," the post on Instagram read.