Boyd volleyed home from the edge of the area in the 44th minute to seal a 1-0 victory for Killie in a match that Hibs needed to win to avoid an unwanted extension to their season.
The match was subjected to a television black-out after Hibs refused permission for BT Sport to screen the play-off decider because they had hosted their quota of live games this season.
But there was no hiding their continuing run of dreadful results which leave them in danger of joining Edinburgh rivals Hearts in next season's Championship.
Hibs have only taken four points from a possible 39, won one game since their new year derby victory, and they proved the fall guys in a five-way battle to avoid the play-off, despite beginning their post-split fixtures, which yielded just one point, in seventh place.
Terry Butcher's side have only scored two goals in eight games and neither the recalled James Collins or Paul Heffernan looked likely to improve that record, despite Hibs dominating the first half. Killie improved after the break and could have added to their tally.
Hibs started on the front foot, but Killie defended a series of corners and Boyd found the net in the 13th minute, although the flag was already up when he latched on to Jackson Irvine's header.
Collins had a header saved and Hibs had a better chance when the forward harassed Lee Ashcroft as the ball bounced on the edge of the box and forced it into the path of Scott Robertson, who saw his low left-footed shot blocked by Craig Samson.
Vitalijs Maksimenko got his head to a powerful first-time effort from Jordon Forster to divert it wide and Barry Nicholson cleared off the line after Robertson glanced a header from Duncan Watmore's corner.
Hibs remained on top and Forster headed a good chance wide from a long free-kick by Liam Craig, with Michael Nelson claiming he had been pulled down in the area.
The incident saw Maksimenko suffer a head knock that forced him off in the 33rd minute. Midfielder Sammy Clingan came on and Manuel Pascali dropped to centre-back.
The visitors enjoyed a good spell of possession which culminated in their opener.
Boyd made two yards of space on the edge of the box to meet Nicholson's driven cross and that was all he needed as he took a step back and volleyed the ball out of the reach of Ben Williams' right hand.
Hibs now needed to score two goals in a game for the first time in more than two months, but they almost replied in the 52nd minute when some goal-line defending repelled them during a frantic scramble following a corner.
Killie were showing improved composure on the ball and posing a threat on the break and Williams palmed Rory McKenzie's strike after the forward played a one-two with Boyd.
The goalscorer had another good chance when Ross Barbour's cross found him unmarked 10 yards out. He headed the ball down towards the far corner, but Williams got down well to push it away. Boyd then fired over under pressure following Nicholson's square pass.
Killie grew in confidence, with Alexei Eremenko and Clingan dominating possession. The former set up Boyd with some great skill, but the striker's scuffed left-footed shot was blocked.
All of a sudden Hibs gave their support a much-needed lift when they got the ball to Craig on the edge of the box and he fired a powerful strike that cannoned off the underside of the bar and out.
Butcher brought on winger Alex Harris and Hibs belatedly put the visitors under sustained pressure. Substitute Owain Tudur Jones saw several headers blocked, one heroically by Pascali, and Samson saved from Harris.
But Williams saved well from Eremenko as Killie finished the game in the Hibs half. The Leith side now have until May 21 to find some confidence for a trip to Falkirk, Queen of the South or Hamilton in the first leg of their play-off.