The visitors threatened first on 18 minutes when Alvaro brought a flying save from Owain Fon Williams with a blistering 25-yard drive.
County responded with a curling free kick from Michael Rose that cleared the crossbar.
The Hatters stunned the La Liga outfit with a goal on 20 minutes. Rose's free kick from the right was powerfully headed home by Gianluca Havern at the far post.
Two minutes later it should have been 2-0 but Greg Tansey missed his kick in front of goal after Johnny Mullins had brilliantly created the opportunity.
Real began to get their game going and the dangerous Asier saw a shot blocked and a powerful volley fly just wide within a matter of minutes.
Asier then set up a chance for Bueno but Fon Williams pulled off a terrific pointy-blank save.
The equaliser eventually came eight minutes before the break when the Hatters failed to clear their lines from a free kick and Nivaldo blasted home from close range.
County almost regained the lead three minutes later when David Poole volleyed wide at the far post after Michael Raynes had nodded Tansey's free kick back across goal.
The visitors made County work hard in the second half with their slick passing game which enabled them to retain possession for long periods.
The Hatters had a sight of goal on the hour when Carl Baker was brought down by Preito which earned the Spaniard a booking. Rose hit the wall with the free kick.
Manucho the caused panic with a surging run and shot that brought another fine save out of Fon Williams.
Valladolid's pressure finally paid off when Gonzalez scored from the rebound after Romero's shot rebounded off the foot of the post.
And they wrapped things up just before the end when Romero clipped the ball into the box to Manucho who drove a powerful left foot drive across Fon Williams into the bottom corner.
County@ Fon Williams; Mullins, Raynes, Havern, Rose; Johnson, Turnbull, Tansey (Vincent), Baker (Pilkington); Poole, P Thompson (Griffin).
Unused subs: Gerrard, Edwards, Roberts, Halls
Attendance: 1,993
