A run of seven league games undefeated had taken the Kings to within a point and a place behind the twelfth placed Pitmen, who had lost their last three games.
The Pitmen had bolstered their squad ahead of the game with the return of striker Dan Sweeney from Solihull Moors.
The Pitmen made a strong start with Sweeney having an early effort charged down and the home side moving the ball around well and winning a series of corners.
In the 25th minute Kings Langley's Stephen Ward found space in the home area and chipped the ball over Shaun Rowley to give the visitors an unexpected lead and spark a disastrous 15 minutes for Hednesford.
Jordan Parkes was allowed too much time on the ball as he drilled home from outside the area to double the deficit in the 37th minute.
Ward claimed his second of the afternoon when he finished from inside the area to complete a dismal spell for the home side.
Reece King pulled one back for the Pitmen just before half time, heading in from close range when Melvin Minter parried Tom Fry's rasping shot.
The second half could not match the first for goals as Kings Langley controlled the game for long spells of play.
A double save from Rowley kept then scoreline down, firstly keeping out an effort from Parkes before preventing Mitchell Weiss bundling in the rebound.
The visors were awarded a controversial free kick in the Pitmen's area for an alleged back pass, the defensive wall did its job and Rowley claimed the loose ball.
In the closing moments Osebi Abadaki had a shot cleared off the line after substitute Danny Glover had won a corner.
There would be no further goals as Kings Langley maintained their unbeaten record while Hednesford Town slumped to a fourth straight defeat.
Hednesford Town; Rowley, Reid, Griffiths, Bailey (c), Gatter, Hallahan (O'Hanlon 67), Fry (Hodge 56) King, Sweeney, Hewlett (Glover 75), Abadaki. Subnot used; Sanali
Kings Langley; Minter, Anderson, Connolly, Hitchcock, Adebiyi, Johnson, Ward (Toiney-Pendred 70), Collins (c) (Williams 45), Crawford, Weiss (Lindsell 87), Parkes.