Mr Bachchan received the prize for his role in Shoojit Sircar's Piku, in which he played the cantankerous old Bhashkor Banerjee. This is Mr Bachchan's fourth Best Actor win after Agneepath, Black and Paa.
Mr Bachchan's actress-politician wife Jaya Bachchan, son Abhishek and daughter-in-law Aishwarya Rai accompanied him to the ceremony.
Ms Ranaut, wearing strapless silver gown, took home the trophy for her double role in Aanand L Rai's Tanu Weds Manu Returns. This is Kangana Ranaut's third National Award - she won the Best Supporting Actress award for Fashion and Best Actress for Queen.
Actress Kalki Koechlin, dressed in a sari, collected Special Jury Award for Margarita, With A Straw.
Baahubali, which won Best Feature Film and Special Effects awards, was represented by director SS Rajamouli.
Acclaimed period film Bajirao Mastani, starring Ranveer Singh, Deepika Padukone and Priyanka Chopra, won in seven categories, including a prize for director Sanjay Leela Bhansali.
Tanvi Azmi received the Best Supporting Actress award for her role in Bajirao Mastani.
Kabir Khan collected Bajrangi Bhaijaan's Best Popular Film Providing Wholesome Entertainment award.
Masaan's Neeraj Ghaywan won Best Debut Director.
Best Choreographer (for Bajirao Mastani) awardee Remo D' Souza collected his trophy.
Producer Maneesh Sharma and Sharad Kataria collected the award for Dum Laga Ke Haisha, which won Best Hindi Film.
Manoj Kumar received the Dadasaheb Phalke Award.
The National Film Awards, which honour the best in mainstream and regional cinema, were announced in March.