Pennock held the same role under the management of Mike Phelan in 2016, having previously been in charge of the Club’s Academy for two-and-a-half years, before leaving the Tigers at the same time as Phelan halfway through last season.
He returns to the KCOM Stadium having spent a short period in charge of Welsh Premier League side Aberystwyth Town.
Speaking after arriving back in East Yorkshire, Pennock said: “I’m delighted but a little bit shocked too. It’s been a bit of a whirlwind few days but I couldn’t be happier to be back.
“I was on holiday this week and got a phone call from the Vice-Chairman who asked me if I was interested in coming back. I met up with him and the manager yesterday and it seemed to go really well and we agreed terms really quickly.
“I didn’t want to leave the Club in the first place and I think most people are very aware of that. Mike Phelan gave me the opportunity to step up to the first team to begin with and I really enjoyed that experience. Unfortunately when Mick and the rest of the staff left then Marco Silva made it clear he wanted to work with his own staff which is completely understandable.
“I was offered the chance to go back to the Academy but I’d enjoyed my time with the first team so much that I decided I didn’t want to go back. I left on good terms with the Club and thankfully I’ve been able to come back to a Club I’ve really enjoyed working for.
“It’s always good to work with new coaches and I really look forward to working with Leonid and the rest of the staff. We’ve got a meeting coming up to talk through pre-season and I look forward to talking more with him and getting to know him.
“I wouldn’t be surprised if part of the reason the Club have asked me to come back is to help some of the Academy players with the transition to the first team. We had a number of players step up to the first team last season and I’d expect more to come through the ranks again this coming season so hopefully I can help the manager get to know our young players a lot quicker.
“I’m a football person and I really enjoyed my short time with Aberystwyth Town. I’ve got to thank them for making this move as simple as it has been and I wish them all the best for the coming season.
“I’m now really excited and looking forward to seeing what next season will bring. It promises to be an interesting season but hopefully it will ultimately be a successful one.”