Ryder took the early exchanges and looked to be in control through the first six rounds until Blackwell backed him up and hurt ‘The Gorilla’ in the seventh forcing Howard Foster to step in.
A crushing body shot in the first 20 seconds by former light-heavyweight world champion Nathan Cleverly announced the Welshman’s return to the divison.
‘Clev’ is attempting to comeback from his loss to old rival Tony Bellew at the 200lb limit and made easy work of Thomas Man to move on to a possible shot at WBA title holder Juergen Braehmer.
In an all-out war, Scotty Cardle claimed the vacant British lightweight title with a unanimous decision in a closely-fought contest with Craig Evans.
The pre-fight needle between the two added to the intensity of the contest, which was edged by Cardle in the opening six rounds. The Joe Gallagher-trained fighter was then guilty of taking his foot off the gas between rounds six and ten but came on strong towards the end to seal a 116-112 win on all three scorecards.
Dave Ryan kept hold of his Commonwealth super lightweight title with an entertaining stoppage win over John Wayne Hibbert.
Ryan, 32, pounded Hibbert with combinations until he hit the floor early in the ninth round before dropping him again following some flush shots. A third knockdown was avoided when referee Victor Loughlin stepped in to save a battered Hibbert from more punishment.
In the opening bout, former British amateur star Lucien Reid made a successful pro debut in stopping Elemir Rafael in the fourth and final round of their encounter.