Though the decision was taken by the party's West Bengal secretariat on Wednesday, the announcement was made today after an approval from the Politburo -- CPM's top decision making body.
In a statement, Mr Mishra said that despite being warned, Mr Banerjee failed to correct himself and continued to tarnish the image of the party.
He added, "For gross anti-party activity, Ritabrata Banerjee is expelled from the primary membership of the party."
Among the top reasons for action against Mr Banerjee was his personal life and personal indiscretions that had led to more than one woman, including his ex-wife, to complain to the CPM about him.
In a recent interview to a Bengali news channel, he criticised the party and its central leadership. Mr Banerjee also lambasted the probe commission, constituted to probe the charges of anti-party activities against him. The commission was headed by the party's Politburo member Md Salim.
He even said, "Md Salim became a Politburo member only because of a minority quota in the Politburo. How can you have quotas in the Politburo."
Mr Banerjee was suspended from the party in June for three months after allegations of breaking the party's discipline.
Following this, the CPI(M)'s West Bengal state committee removed Mr Banerjee and had sent a recommendation to the Central Committee seeking his punishment, the party's statement issued today said.
"On September 11, in a television interview he publicly tried to malign the party and on that basis the state secretariat decided to expel him (Mr Banerjee) from the party," Mr Mishra said in the statement.
Mr Banerjee had earlier said that someone had to bell the cat, he had done it and had no regrets.
He joined the CPM in 1996 as a student leader, was general secretary of the student wing, SFI, from 2008 to 2016 and was elected as a Rajya Sabha member in 2014.
(With inputs from PTI)