The White Hart Lane defender has been welcomed back into the national fold after focussing on his club form.
The former Sporting Lisbon defender opted to be left out of the national age-grade reckoning late last year to focus on establishing himself at the North London club in his favoured position of centre-half.
With Dier now seemingly first choice alongside Jan Vertonghen for Mauricio Pochettino’s side, the Spurs man has now returned to the England under-21 reckoning.
Southgate has welcomed Dier back with open arms and was full of praise for the way the defender has established himself at Tottenham.
“Eric felt he needed to go away and work on his game - he wanted to establish himself at centre back and he's done that which is great credit to him,” ESPN quote Southgate as saying.
"I did speak to him before this squad because I wanted to check he wanted to be a part of it but he said all along it was a temporary thing and he needed more time to work on his game and he's delighted to be back in the fray."
Dier was utilised as a right-back earlier in the campaign at Tottenham, but has seemingly found his home at the heart of Spurs’ rearguard in place of Federico Fazio.
The 21-year-old has started 16 Premier League games for Spurs this season and impressed more often than not, despite a poor showing at Old Trafford last Sunday.
Dier will now be in the reckoning to represent England at the under-21 European Championships this summer, which take place in the Czech Republic.