The movie, directed by Mukul S Anand, also featured Tamil superstar Rajinikanth.
"25 years of HUM .. Quite unbelievable time lapse," Bachchan, 73, posted on Twitter.
The actor won the Filmfare Best Actor Award for "Hum" in 1992.
Govinda, Kimi Katkar, Deepa Sahi, Shilpa Shirodkar, Danny Denzongpa, Anupam Kher and Kader Khan were also part of the superhit film.