Main construction is set to begin on the Grimshaw-designed development, which will deliver 235,000 sq ft of new-build office space above the northern entrance to Paddington Station, with views across the Grand Union Canal.
Enabling works commenced last June, paving the way for the main build phase to get under way in March.
Mace has been named preferred bidder for the scheme, with the contract expected to be formally signed shortly.
The development is scheduled to complete in autumn 2028.