The Baggies, overseen by caretaker boss Keith Downing, looked worryingly short of confidence in a first half lacking in quality from either side.
They fell behind in the 28th minute when Jake Livermore finished a Tigers counter-attack, the on-loan Tottenham midfielder slipping the ball beneath Ben Foster having been teed up by Danny Graham.
West Brom improved after the break and they equalised with four minutes of normal time remaining.
In a neat move by the hosts, Vydra, who is on loan from Udinese, collected the ball from his fellow substitute Zoltan Gera and slotted in his maiden goal for Albion.
It was the first point West Brom have secured in five games and they remain 16th in the table, while Hull stay 12th.
It took 10 minutes for the contest's first attempt on goal to be registered, with James Chester heading off-target from Tom Huddlestone's corner.
And there was little in the way of action thereafter until Livermore broke the deadlock.
James Morrison lost possession by the edge of the box and went to ground in it under the attentions of Huddlestone, who appeared to have made little, if any, contact with the Albion man.
Morrison looked to referee Jonathan Moss but play continued, with the ball coming to David Meyler, who hoisted it forward for Graham. The striker had the space to take it forward and his neat pass set up Livermore to beat Foster with a low strike.
West Brom needed a response, but they continued to struggle to get much going, and Meyler cracked a shot at goal that was deflected behind.
A chance was presented to Morrison just before half-time, but he skewed it horribly and Albion then won a free-kick in a useful-looking position that amounted to nothing.
With the Baggies seeming in desperate need of some fresh impetus, Downing put Saido Berahino on for Scott Sinclair at the interval.
And the home side looked much livelier in the opening stages of the second half, with Berahino firing a shot against Allan McGregor and Youssouf Mulumbu seeing his drive deflect over.
West Brom kept pushing and Shane Long missed with an attempt before Gareth McAuley's header was gathered by McGregor.
But Foster - making his first appearance since sustaining a stress fracture in his foot in August - was then called upon to make a smart double save, denying Huddlestone and Ahmed Elmohamady in quick succession.
Downing reacted by bringing on Vydra for Stephane Sessegnon and soon after Berahino headed wide weakly, when he might have done better, from a corner before winning one with a more powerful shot.
Zoltan Gera came on for Liam Ridgewell in Albion's final substitution and after good work from Long, the midfielder laid the ball to Vydra, who converted past McGregor.
Huddlestone sent a free-kick narrowly off-target towards the end before the final whistle confirmed the points would be shared.