The on-off pair spent two days holed up at a five-star hotel in Monaco before emerging arm in arm, looking loved-up, reports thesun.co.uk.
“They looked so happy, it was sweet,” said a source.
Hamilton, 27, and Scherzinger 33, split in October 2011 after being together for three years. They reasoned out their work schedules, which kept them apart.
Last week, they took a private jet to the French Riviera after the singer finished a gig in Dublin.
Later, Hamilton took his lady love sightseeing on the French Riviera on a rented motorbike.
“They are taking things slowly and trying to avoid the same mistakes. They’re making sure they get every moment they can together,” the source added.