The reported figure for the 22-year-old from Hammersmith is around £50m, with personal terms already agreed over a five-year contract.
Chelsea are still keen on bringing in two more attackers in this transfer window despite being outbid for Olise.
They are currently exploring options to bring in Marc Guiu from Barcelona, and Jhon Duran from Aston Villa.
This comes after already selling them Dutch left-back and Champions League finalist Ian Maatsen, and look set to complete the signing of youngster Omari Kellyman today.
