The ex-Chelsea youngster is set to join the Cottagers on an initial season-long loan, with the deal expected to be completed by the middle of the week.
Fulham will have the option to make Aina’s loan a permanent transfer for a figure in the region of £11m.
Former England youth international Aina is a graduate of Chelsea’s academy and spent over a decade at the club.
He spent the 2017-18 campaign away on loan at Hull before making a season-long loan move to Torino the following year.
The Serie A side took up the option to make Aina’s move from Chelsea permanent in June 2019. The 23-year-old made 37 appearances for Torino last season.