The winger crashed home with ten minutes remaining to cancel out Emmanuel Adebayor's opener and set up the Hammers' turnaround.
Modibo Maiga won it for the visitors on 85 minutes and Jarvis was thrilled to secure a place in the last four of the Capital One Cup.
"It was a fantastic result for us and just what we needed," Jarvis told whufc.com. "This is a tough place to come to, so we're delighted with the win.
"This shows what a great squad we've got, we're really working hard for each other and it paid off tonight."
Jarvis' goal was crucial to the Hammers fightback and he admitted that he could not have picked a better moment to open his account for the campaign.
He added: "All that was going through my mind when I saw Matt Taylor laying it off was to get on the end of it and hit the target.
"I did that and I'm absolutely delighted that it went in, especially in front of the West Ham fans.
"That's what it's all about, scoring goals, and to do it in front of your own fans is a fantastic experience and let's hope we can get a few more."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball