Harlequins scored three tries in the final 10 minutes to run out 38-14 winners at Newcastle and snap a three-game losing Premiership streak.
James Chisholm's converted try handed Quins an early lead but the game evolved into a tight contest, which saw Adam Radwan level for bottom-of-the-table Newcastle.
England star Marcus Smith crossed to restore his side's advantage and extended the visitors' lead from the tee early in the second half.
Ben Redshaw's try reduced Newcastle's arrears.
But a late burst from Harlequins saw Jack Walker, Oscar Beard and Sam Riley all cross the try line late on for a fourth Premiership win this season.
Victory moves them up to sixth, while the Falcons remain rock bottom with just two wins from 10 games.