The Wolves striker was called into the squad as a replacement for the injured Saido Berahino and has settled quickly into the group at their base in Olomouc after arriving in the early evening.
He trained for the first time at Sigma Olomouc’s Ander Stadium on Saturday, as the Three Lions prepare to take on Sweden in their second Group B game on Sunday.
Afobe has scored 32 goals this season for MK Dons and Wolves
And the head coach revealed he’s been impressed with the former Arsenal man since he first named him in his long squad for the tournament last month.
"I’ve been really impressed just talking to him," said Southgate.
"When I put him on the long list, he was so desperate to be involved, he kept sending messages, ‘I’m ready if needed’ and when I spoke to him: ‘Yeah, I’m keeping myself fit, I’ve got a programme, I had 50 games last year but I can play another 20’.
"So he’s really impressed me as a character, he’s brought raw enthusiasm to the group because, for him, it’s difficult because we just said goodbye to Saido who’s been a massive part of why we’ve got here.
"But it’s great to get Benik in, he’s fresh and he can’t wait to be involved."
Afobe is no stranger to the England set-up having represented the Three Lions at numerous levels in previous years.
Afobe with Harry Kane during the U19 Euro Championship Finals in 2012
He was part of the U17s squad which won the Euro title in 2010, along with the likes of Jack Butland, Nathaniel Chalobah, Luke Garbutt and Ben Gibson and has quickly made himself a popular member of the group.
"He knows quite a lot of the lads, because he’s played with the U17s, U19s and U21s and a lot of these boys grew up together in the side that won the European Championship at U17 level," explained Southgate.
"So in terms of England, he’s got a lot of experience and has tremendous enthusiasm to be here and when I spoke to him, he was ready to cancel his holiday straight away, telling me how he was keeping his fitness up and wishing us good luck.
"At U17 level [in 2010], it was Saido who actually came into the squad late because of an injury and he’d been talking to Benik throughout this week and the irony is that Saido picks up the injury and Benik is the one that benefits from it.
"He adds some more energy and enthusiasm coming into it at this stage and is very much looking forward to it."
