However, shortly after joining up with Aidy Boothroyd's squad he was told to instead join up with Gareth Southgate's senior side at St George's Park.
“It's been a crazy day but getting my first [senior] international call-up is an amazing feeling,” he said in an interview with The FA.
“Today has been a very long day for me because I had to travel to Bristol first for the U21s and then getting told that I have to come over here to St. George's Park, it's been a crazy experience but I'm delighted to get the call and it's a nice feeling to be here as well.
“I thought the manager [Aidy Boothroyd] was joking. I was shocked and then when I heard that I actually had to go over, I couldn't believe it. I was delighted.
"It's a dream come true. Now I've got to work hard, enjoy every moment and keep working to just hopefully make an impact when I get the opportunity.
“Everybody here is very humble and they're very nice. They make sure you're comfortable. No one has an ego here so
Hudson-Odoi was a member of England’s Under-17 World Cup-winning side in 2017 and has been capped from Under-16 through to Under-19 level.
He has yet to start a Premier League game for Chelsea, with the majority of his 19 appearances this season coming in the Europa League and domestic cup competitions.
Hudson-Odoi handed in a transfer request to try and force through a move, but Chelsea held firm.
His current contract runs out in the summer of 2020 and the winger has so far rejected all offers by Chelsea to renew it, despite promises of improved playing time and increased wages.
Meanwhile, Manchester United defender Luke Shaw has pulled out of the England squad through injury.
The 23-year-old is the fourth player to withdraw from the squad following John Stones, Fabian Delph and Ruben Loftus-Cheek.
It means Southgate has a 23-man squad to choose from after Southampton’s James Ward-Prowse was added to the squad earlier on Monday.