Tries from Aleki Lutui and David Lemi had seen Worcester take control of the Aviva Premiership clash before a breathtaking finale.
Semisi Taulava crashed over for his first try for the club and in then dying seconds a flowing backs move was completed by Jon Clarke on his debut to a thundering ovation from a partisan home crowd.
The result capped back-to-back try bonus points for Worcester and Hill was clearly pleased by the ruthless manner his team had driven home their advantage in the closing stages.
He said: "It was a vital game to win. It could have gone either way for our season with this one.
"We have performed so well but hadn't got the rewards for it. Tonight we had to get something for all the effort the players have put in.
"There were nerves leading into this game, it was massive for us. We thought the Northampton second half would be a turning point for us and we had to prove it against Irish.
"We made hard work of it, but you can see the relief written all over the faces. It really is absolutely crucial for us.
"The players have worked hard on this attacking game," he added. "You can see some of the flair with our handling, the pop passes with the ball and out the back of the hand. The little kicks through.
"We are trying things and you could see the hunger. After scoring three tries we were running back and wanting that fourth score.
"Last year we were content with winning games, now the mentality is different and we want to score more.
"Last season we only scored six tries in the first set of games, we have beaten that easily now and there is a real hunger to score now.
"If you are scoring just one try a game, like we did last season, you always open yourself up to a breakaway try. If you are scoring two, three or four it gives you that cushion."
Hill also praised the impact of Jonny Arr and Josh Matavesi as they were called into the starting line-up.
"Neither have had much rugby recently, but both were very good tonight," he smiled.
"Jonny Arr speeded the ball up. He hasn't done 80 minutes for a long old time, but I thought he was superb tonight. He allowed us to play at real pace.
"Josh Matavesi has improved with his defence and in attack he opens up possibilities for us."
The only negative for Warriors was wing Nikki Walker limping out of the game after less than ten minutes.
Hill added: "Nikki tweaked in the warm-up before the game. It tightened and cramped up on him. It was a tough ask for Jon Clarke coming on the wing. But he did a very good job for us."