The 26-year-old has scored 11 times this campaign and will join the club in June after agreeing a three-year deal.
Loy signed for the Bairns from Carlisle in 2013 after previous spells at Rangers, Dunfermline and St Mirren.
He was nominated for the PFA Championship Player of the Year award last season after netting 21 times.
Dundee have signed Falkirk striker Rory Loy on a pre-contract as manager Paul Hartley begins his squad rebuilding for next season.