Meanwhile, a beat-the-deadline move saw the Millers bring in left-back Sebastian Revan on loan from Aston Villa for the rest of the season.
Raven can also operate across all defensive positions as well as in midfield. He has had a previous loan spell in the EFL at Grimsby Town.
A host of League One sides including Barnsley and Blackpool had been in the race to sign Kayode, but he is now heading to Cumbria.
The 23-year-old has seen his development with the Millers badly affected by several injuries.
After suffering a pre-season hamstring tear in the summer of 2022, Kayode joined MK Dons on loan for the 2022-23 campaign.
He injured his knee during his time in Buckinghamshire and then had surgery on a damaged quad that ended his season.
Kayode has had previous loans at Carlisle, Chesterfield and Gateshead.
The Republic of Ireland under-21 international has made 38 first-team appearances for the Millers and found the net three times.