Shatrughan Sinha's first acting opportunity was playing a Pakistani military officer in Dev Anand's Prem Pujari. Subsequently, he got a small role as a police inspector in Mohan Sehgal's Sajan in 1969. The release of Prem Pujari was delayed, so his first released film was Sajan. He later appeared in villainous role in Pyar Hi Pyar, Banphool, Manmohan Desai's Rampur Ka Laxman and Bhai Ho Toh Aisa, Sultan Ahmed's Heera and in Vijay Anand's Blackmail. He played supporting roles in many films before appearing in Gulzar's Mere Apne in 1971. He was cast along with his future wife Poonam Sinha then called as Komal in the movie "Sabak" (1973). He played supporting roles in Khilona, Dulal Guha's Dost in 1974, Aa Gale Lag Jaa, Jheel Ke Us Paar and Gambler in 1970. He acted with Amitabh Bachchan in films like Raaste Ka Paththar, Yaar Meri Zindagi, Shaan and Kala Paththar which were flops and later acted in Bombay To Goa, Dostana and Naseeb. His films as the lead hero between 1970 to 1975 were not hits. His first successful film as lead hero was in Kalicharan in 1976. Subhash Ghai had went with story of Kalicharan to NN Sippy and said he wanted to direct his first film. N.N.Sippy got ready to produce after few days, but wanted to cast only Rajesh Khanna in the lead role of Kalicharan. Then only when N.N.Sippy confirmed with Rajesh Khanna that Rajesh did not have dates for the years 1976 and 1977, Sippy asked Subhash Ghai to go ahead with the script and direct Kaalicharan with Shatrughan Sinha in the lead. Some of his notable films as lead hero were Ab Kya Hoga, Khan Dost, Yaaraon Ka Yaar, Dillagi, Vishwanath, Muqabla, Jaani Dushman. He then became a bankable action hero from early eighties to mid-nineties. He co-starred with Sanjeev Kumar in Bereham, Hathkadi, Bad Aur Badnaam, Chehre Pe Chehra, Hirasat and Qatl. He starred in Hrishikesh Mukherjee's Naram Garam, Brij's Bombay 405 Miles and Taqdeer. He has sung the song Ek Baat Suni Hai Chachaji with singer Sushma Shresta in the film Naram Garam in 1981 composed by R.D.Burman. However when his films as lead hero like Prakash Mehra's Jawalamukhi, Amjad Khan's Chor Police and Ameer Aadmi Garib Aadmi and Raj Khosla's Mera Dost Meraa Dushman became flops despite being appreciated by critics, there was threat to his career as lead hero . He then bounced back by bagging roles in films with lead hero as Rajesh Khanna in films like Dil E Nadan, Aaj Ka M.L.A Ram Avtaar, Maqsad, Paapi Pet Ka Sawal Hai. His other hit films in the mid-eighties included Jeene Nahi Doonga, Bhawani Junction, Aandhi-Toofan, Ramkali, Ilzaam, Asli Naqli. He then went to star with Jeetendra in Hoshiyar, Khudgarz, Ranbhoomi and Mulzim. He co-starred with Dharmendra in Insaniyat Ke Dushman, Loha (1987), Aag Hi Aag (1987), Hawalaat, Zalzala. His films like Telephone (1985), Sherni (1988), Khoon Bhari Maang (1988), Adharm (1992). He starred with Raajkumar in Betaaj Badshah in 1994 and Salman Khan in Chaand Kaa Tukdaa in 1994. Sinha credited Rajesh Khanna for getting Kaalicharan and for revival of his career as lead hero in the 1980's however their friendship got affected when Shatrughan Sinha stood as the BJP candidate against Rajesh Khanna in 1992 election. Though as a Congress candidate Khanna had defeated Sinha by 25000 margin of votes, Khanna was disappointed at Sinha for standing against him in the elections. In 2008, he became a judge on The Great Indian Laughter Challenge show, season 4 on STAR One TV. On 3 October 2009, Sinha appeared on Sony Entertainment Television Asia's show Dus Ka Dum season 2 as host for a special episode. He is currently hosting the Bhojpuri version of the popular game show Kaun Banega Crorepati on Mahuaa channel.