Everton want to add further quality to their ranks following a hectic finale to the summer transfer window, with Zouma identified as a loan target.
The deal sheet for the loan agreement was submitted to the Premier League before the 5 p.m. deadline on Thursday, giving Everton and Chelsea extra time to finalise the details.
The Toffees made a late move for the 23-year-old on deadline day but had to wait until Friday to learn if their bid had been successful.
Everton were also linked with a move for out of favour Manchester United star Marcos Rojo, but have not been able to make head way on the deal.
Manchester United did enquire about signing the defender earlier this week but it seems negotiations never took off and the centre-back will continue at the Wanda Metropolitano.
However, according to Spanish outlet Marca, the Catalan giants will be granted first option on Mina if they want to bring him back to the Nou Camp in the future.
The France global spent last season on loan to Stoke City, but was left out of Chelsea's pre-season trip to Australia due to injury.
It looks like Mourinho is keen to be reunited with Zouma at Old Trafford but it remains to be seen whether Chelsea will agree to sell to Manchester United or pursue a loan deal with Everton.
He was loaned to Stoke the following summer and appeared in 34 Premier League games but could not prevent the Potters finishing with the joint-worst defensive record in the division and suffering relegation.