The 42-year-old actress debuted in the 1992 romantic drama "Bekhudi", alongside another debutant Kamal Sadanah.
Kajol took to Twitter where she shared an old picture with her parents, actress Tanuja and director-producer Shomu Mukherjee.
"Throwback to 25 years back. So much love for so long. Truly humbled!" she wrote.
Tanuja also featured in the Rahul Rawail-directed movie, playing the actress' onscreen mother.
Apart from Kajol, her long-time friend and co-star, Shah Rukh Khan also completed 25 years in the film industry on June 25 this year.