Boro missed a number of glaring opportunities and saw Hull go in front late on when Keane Lewis-Potter’s strike shuddered the post and then rebounded off the back of visiting keeper Joe Lumley into the net.
A late second from substitute Mallik Wilks - who scored at the death on the previous occasion these sides met in July, 2020 on the date of City’s previous home triumph at this level against Teessiders - added a second for the hosts.
The loss was compounded by the sight of Dael Fry exiting the fray in the 79th minute, with Warnock fearing he will be out for an extended spell.
It was also a day when Paddy McNair saw a free-kick ruled out for a soft-looking infringement.
On the loss, Warnock said: “It is a shock, really. I don’t know how we have not won the game.
“We have all those chances and the ball hits the goalie on the back of the head...When it is one of those days, it is one of those days, really.
“You are not going to get any better chances what we had today.
“I don't know what else I can do, if I am honest. The chances we created in the second half, apart from running onto the pitch and putting one in, I don’t really see what else I can do.
“We created enough chances, but couldn’t finish them off. We cannot say this week that we did not create enough for the attackers. We created loads of chances for them.
“The goalie made a brilliant save off Paddy (McNair), but other than that we’ve had some cracking chances.”
On Hull’s fortunate opener, he added: “He is our best striker at the minute, Joe. He missed a header last week and took it well today..What more can you say.
Dael Fry is out for goodness knows how long. Grant Hall pulled up yesterday and is out. Martin Payero didn’t feel right yesterday. I don’t know what more I say to paint a more bleak picture at the minute. We are a bit short.
“Dael got a smashed arm in his face, which unfortunately nobody saw. The referee was in a poor position and the fourth official saw it, I am sure. I thought it could have easily been a red card, having watched it back.
“He got up too quickly and tried to tackle and pulled his stomach or groin, but he couldn’t move after that.
“I think if the international break was four or five weeks ong, then yes (it would be welcome). But it’s only two weeks, so it will be a difficult period.”