The 20-year-old midfielder has returned to The Valley on a short-term spell for the remainder of the season following his loan stint with MK Dons.
Poyet came through the youth academy at Charlton before making his senior debut for the Addicks in 2014 and has now returned to the London club where he will play under interim boss Karel Fraeye.
Upon his return to Charlton, Poyet told the club's official website: “It feels good to be back.
“Karel Fraeye first made contact with my agent and straight away I was really excited about the idea.
“I spoke to him and we got it done as quickly as possible. I'm just looking forward to the rest of the season.
“I was a little bit nervous last night, but excited about coming in and seeing the boys. I didn't tell any of them that I was coming in, so it was a bit of a surprise to some of them seeing me pull in this morning!
“It's been really nice to see everyone, including staff who have known me over the years, so it's been really nice.
“I've finished my first training session, I really enjoyed it and I'm glad to be back."
READ | @diegopoyet7 thrilled to be a Charlton player again https://t.co/GftakaWRr1#cafcpic.twitter.com/myZlhcvLm0
— Charlton Athletic FC (@CAFCofficial) January 4, 2016