Matty Fryatt grabbed the only goal of the game for the Tigers in the 64th minute when he latched onto a long ball from James Chester and slotted a low shot beyond the advancing Lee Camp.
The strike ensured Forest tasted defeat at the City Ground in a regular season match for the first time since September 2009, although they were unfortunate not to claim at least a point from this encounter.
Billy Davies' men carved out the only chances in a largely dour first half and Hull continued to offer little in attack after the interval.
However, Fryatt's clinical finish was to prove the difference as the visitors closed the gap on their fifth-placed opponents to seven points.
Source: PA
Source: PA