Depleted Hitchin crashed to their seventh defeat in nine games when high-flying Carshalton cruised to victory at a windy Top Field.
Hitchin's line-up was already missing key players when Mark Bridge was stretchered off in the first half. By that time, Carshalton had taken a 17th minute lead through Dale Marvell, who smashed his shot in off the crossbar.
Richard Wilmot kept Carshalton at bay with some good saves, but the visitors extended their lead in the 38th minute when Adrian Stone capitalised on a wind-assisted pass and shot past Wilmot.
Just before the break, though, the Canaries almost pulled one back when Darran Hay's shot was deflected for a corner. In the second half, Mark Burke and Tom Neill both had chances after some concerted pressure.
In the 73rd minute, Nic McDonnell netted from close range to seal Carshalton's victory.
Hitchin Town: Wilmot, Childs, Neill (Mills 74), Burke (McElroy 82), Covington, Scott, Nicholl, Lochhead, Bridge (Duffy 19), Hay, Maynard