Renfrewshire Council had already made £3.5m available for the project - and the final piece of the funding jigsaw arrived today with confirmation of a £1.5m grant from the Scottish Government's Regeneration Capital Grant Fund.
The project will see the existing Paisley Central Library relocated from its existing home adjoining Paisley Museum to the unit at 22 High Street, formerly the Internacionale store, to form a new learning and cultural centre.
The move is part of a wider effort by the council to use culture to transform the fortunes of the town centre, taking place alongside the UK City of Culture 2021 bid.
Work is already under way on a publicly-accessible museum store in a formerly-empty unit at 9 High Street, due to open later this year.
And plans are moving forward for a £49m revamp of Paisley Museum into an international-class destination based around Renfrewshire's unique heritage, which would bring an estimated extra 125,000 visitors per year to the town centre.
The library project will involve a major refurbishment of the building and a new shopfront but will retain the historic façade on the upper levels, in keeping with the rest of the High Street.
The new facility would be managed by Renfrewshire Leisure Ltd and is planned to be open by the end of 2019. A consultation with existing, lapsed and non-users of the current library last year showed they were mainly supportive of the principle of relocating to the High Street.