The ANC said its disciplinary committee found Magashule guilty of violating several rules of the party's constitution, which include failing or refusing to comply with stated party policy, resolutions and regulations.
The decision to oust Magashule - who is aligned with former leader Jacob Zuma's faction within the party - was made after he failed to respond to why he should not be expelled from the party, the ANC said in a statement.
Magashule was suspended from the day-to-day running of the ANC in May 2021 as part of tougher rules for party members charged with corruption.
Shortly after his suspension, Magashule attempted to suspend President Cyril Ramaphosa saying he had the authority to do so as secretary-general, which failed.
Once seen as one of Ramaphosa's main political opponents, the charges against Magashule were over a contract to audit homes with asbestos roofs, between 2014 and 2016, when he was premier of the Free State province. He denies any wrongdoing.
Magashule was not immediately available for a comment.