Former Mamelodi Sundowns ace Pelembe has signed a new one-year contract with the PSL champions with an option.
Zimbabwean Mutizwa has penned a two-year deal with Wits after spending his first season in South Africa on loan at Golden Arrows last term following his arrival from Highlanders.
Clever Boys CEO Jose Ferreira confirmed the pair have been retained, having earlier dismissed speculation linking the club with ex-Bafana Bafana stars Teko Modise and Steven Pienaar.
"We have exercised the option and we keep Knox this coming season," Ferreira tells KickOff.com.
"Pelembe has signed for one year with an option," he adds of the Mozambican, who initially joined the Students in July 2015 from Downs.
Coach Gavin Hunt's side on Thursday announced the capture of midfielder Daylon Claasen.
The MTN8 holders are also assessing Chippa United ace Thamsanqa Sangweni and former Platinum Stars defender Rofhiwa Tshikovhi.