The 72-year-old, who tied the knot on June 3, 1973, with Jaya, took to micro-blogging website Twitter to express his gratitude towards his fans.
"To them that give me their wishes for the Anniversary, my sincere gratitude and love... 42 years of marriage," tweeted Big B on Wednesday.
The duo has worked together in movies like "Abhimaan", "Chupke Chupke" and "Sholay". They had a small wedding affair back then with only close friends and family in attendance.
Big B says though 42 years have passed, "it all seems so very close and immediate."
"Self wishes are the order of the day... they serve both ways. They convey to you the Ef, of my marriage anniversary...and they inform the wife that she has not been forgotten even though she is not in the country at this moment...," he posted on his blog.
"After 42 years it all seems so very close and immediate... the decision to be together .. the information to the elders .. parents first and then .. Khwaja Ahmed Abbas, my first director and then Hrishikesh Mukherjee, Jaya's first director, and ours for many films thereafter...," he added.
Amitabh and Jaya have two children - Shweta and Abhishek. Shweta is the elder one, and is married to businessman Nikhil Nanda. She got married in 1997 and is now based in Delhi. They have two children - Agastya and Navya Naveli.
Abhishek, a Bollywood actor, is married to former beauty queen-turned-actress Aishwarya Rai. They have a daughter named Aaradhya.
