“I will have nothing to do with sewer politics,” he said in a 13-page statement on Thursday.
He won about 44% of the votes in last year’s presidential election which was plagued by allegations of foul play.
However, several MPs from his CCC party later lost their seats in what Mr Chamisa said was sabotage.
Mr Chamisa, a 45-year-old Christian pastor and lawyer, is expected to set up a new party. He said that “giving up or giving in is not an option”.
It is not clear how many of the CCC’s remaining MPs and councillors will follow him.
While he does enjoy significant support, especially in urban areas, his critics say Mr Chamisa’s weak leadership led to deep rifts in the opposition, and that has only helped President Emmerson Mnangagwa cement his grip on power.
In his resignation letter, he said the CCC had been “defiled”, accusing the ruling Zanu-PF party of being behind the move – allegations it denied.
“The original CCC idea has however been contaminated, bastardized, hijacked by ZANU PF through the abuse of State institutions,” he said.
Throughout the statement, the former CCC leader blamed President Emmerson Mnangagwa for a number of issues plaguing Zimbabwe, including “death trap” hospitals, the cholera outbreak and the collapse of social services.
He said multiple people in his party had been bribed to undermine it from within.
In a nod to President Mnangagwa’s reptilian nickname, Mr Chamisa said he refused to “swim in a river with hungry crocodiles”.
President Mnangagwa came to power in 2017 following a bloodless coup that ousted long-time leader Robert Mugabe.
At the time he was seen as a beacon of change and hope for the struggling country.
But high inflation, unemployment and censorship remains rife in Zimbabwe.
Mr Chamisa has been in opposition politics for more than two decades.
During this time, he says he has faced threats to his life, including escaping an alleged assassination attempt in 2022 when his convoy came under attack during by-election campaigns. He also suffered a cracked skull during a clampdown on the opposition in 2007.
He was previously the leader of another party, the MDC, which he left after a power struggle before going on to found the CCC in 2022.