The 66-year-old actor was found dead at his residence on Friday morning. He suffered a cardiac attack.
"Om Puri, if in soul you be, may you remain with your ever infectious smile," Amitabh wrote on his blog.
The 74-year-old thespian also shared that "death, that darkest moment of humanity".
"Took away another soul into its boundless fold and left us all in disbelief," he added.
Big B called Om "a friend, an affable loving colleague and a dynamic talent".
Amitabh, along with his son and actor Abhishek, attended the actor's cremation, which took place at the Oshiwara Eletrical crematorium, here.
He said that the only thing that he could do is to hold his "friend's son in an embrace and transfer strength to him in his young world."
"'Be strong'... is all I can muster... what else can I say... what else can anyone say... they that have lost personally and in relation, shall bear the end, with greater sorrow... who knows," Amitabh added.
The last rites of Om Puri were carried out by his son Ishaan in the presence of his divorced wife Nandita Puri and close friends Ashoke Pandit and Anupam Kher as well as iconic filmmakers like Ketan Mehta, Prakash Jha and Govind Nihlani, actors Shabana Azmi, Shakti Kapoor, Randeep Hooda, Manoj Bajpayee and Ranbir Shorey, Farhan Akhtar and veterans Gulzar, Javed Akhtar and Sonu Nigam.
