A well-taken hat-trick by Junior gave Walsall a deserved victory in an entertaining end of season match.
Craig Burley missed a penalty for Derby after an own goal from Tony Barras and a Fabrizio Ravanelli striker had given them a fighting chance.
Junior opened the scoring after only three minutes. Ian Roper headed on a neat cross from Vinny Samways and Junior headed in from close range.
Darren Wrack had a great chance to increase Walsall’s lead only three minutes later but with only keeper Lee Grant to beat he sliced the shot wide.
It was entertaining football, with both sides having their chances, but the second goal didn't arrive until six minutes after the interval.
Derby's caretaker manager George Burley had brought on young keeper Lee Camp for Grant at half time and the youngster was unlucky to concede the goal.
It came from a cross by Zigor Aranalde which Junior headed from close range. Camp made a good initial save but the ball rolled loose and bounced in off his trailing leg.
Derby were never out of it and they reduced the areas in the 59th minute.
Outstanding midfielder Burley sent in a free-kick and midfielder Simo Valakari fired a shot which seemed to be going well wide until it took a vicious deflection off defender Barras for an own goal.
Just two minutes later the Rams should have been level.
Roper was pulled up for a foul in the box on Ravanelli, but Burley's spot kick was brilliantly saved by James Walker and the Italian’s close-range follow-up shot went well over.
Walsall increased the lead in the 70th minute when an attempted clearance rebounded off substitute Pedro Matias for Junior to beat Camp from close range.
Derby continued to fight and scored a second goal with seven minutes to go.
Carl Robinson gave away a free-kick for a foul on Izale McLeod and Ravenelli hammered home a brilliant 20-yard free-kick.