Dorival, also a former Brazil coach, was dismissed after Sunday's 1-0 home loss to Internacional in Brazil's Serie A, which left 16th-placed Corinthians two points above the relegation zone.
Former midfielder Diniz, who briefly played for Corinthians, led Fluminense to the Copa Libertadores title in 2023, before winning the Recopa Sudamericana the following year.
During that same period, he also served as Brazil's interim coach for six months, before he was sacked in January 2024 following Brazil's first home defeat in a World Cup qualifying match, a 1-0 loss to Argentina.
Corinthians visit Argentine side Platense in the Copa Libertadores on Thursday.