The new ministers were administered the oath of office and secrecy at the Glass House at Raj Bhavan by Governor Vajubhai Vala amid tight security.
The new inductees are Satish Jarkiholi, M B Patil, C S Shivalli, M T B Nagaraj, E Tukaram, P T Parameshwar Naik, Rahim Khan and R B Thimmapur, with seven of them hailing from north Karnataka.
Congress President Rahul Gandhi had given the go-ahead for the rejig Friday night after the state party leaders and AICC in-charge of Karnataka K C Venugopal met him and discussed the issue.
Ramesh Jarkiholi, who has allegedly been hobnobbing with BJP leaders and not attending Cabinet and party meetings, has been replaced by his brother Satish Jarkiholi.
Shankar is an Independent lawmaker who faced the axe over his reported reluctance to be an associate member of the Congress.