Connor eventually joined the Black and Whites in the off-season after a transfer saga with Huddersfield and he scored the winning try 10 minutes from time having only replaced full-back Jamie Shaul on the hour mark.
Scott Grix, making the first appearance of his second spell at Wakefield, had appeared to have done enough to earn Trinity the points after a dull first half yielded just six points from the boot of Marc Sneyd and a Sam Williams penalty.
Wakefield had one last chance to snatch the victory but Grix was unable to touch down Tom Johnstone's kick in the dying seconds.
Last year's Challenge Cup winners Hull would have been desperate to lay down an early marker but pouring rain and freezing temperatures made for a tough first outing.At the end of a predictably scrappy first half, the Black and Whites were good value for their 6-2 lead.
Wakefield suffered a blow just two minutes in when Anthony England, who had led Trinity's defensive effort in the game's opening set, was forced off with a head injury.
The conditions were a throwback to the pre-Super League era so it was no surprise when Sneyd quickly pointed to the posts after Mikey Sio was penalised for not clearing the ruck.
The Hull scrum-half slotted over the penalty from in front and took advantage of more Wakefield indiscipline on two further occasions to make it 6-0 midway through the first half.
Wakefield had their chance to respond when Danny Kirmond was held down in the tackle and debutant Williams made no mistake from just to the right of the sticks.
In between the penalties chances were in short supply, Hull winger Fetuli Talanoa twice being halted by strong tackles just short of the line and Wakefield stand-off Jacob Miller sliding into the advertising hoardings attempting to ground Williams' grubber kick.
The game's first try eventually came four minutes into the second half courtesy of Grix's smart thinking.Faced by a wall of Hull defenders, the Trinity full-back sent a kick through the legs of opposite number Shaul before diving on the loose ball.
Williams added the extras to edge Wakefield in front for the first time but a 40/20 from Sneyd left the hosts clinging onto their slender lead.
Trinity survived more pressure on the back of testing Sneyd kicks, although frequent mistakes with ball in hand left them camped in their own half.
Hull's pressure finally told as Connor pounced on a mistake by Ben Jones-Bishop from Sneyd's cross-field kick to touch down just 10 minutes after his introduction.
Wakefield launched one last attack with seconds remaining but Grix was unable to get to Johnstone's sliding kick as Hull held on for a fifth successive win over Trinity.
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