Long made his England U18 début in April 2011, coming on as a second-half substitute during a 1–1 draw with Italy in Carpi. Following a successful 2012–13 season, Long was selected in the provisional 35-man squad for the 2013 FIFA Under 20 World Cup, and was later confirmed as part of the 21-man squad for the finals themselves. Long featured in a pre-tournament practice match against Uruguay, but failed to make any competitive appearances during the tournament. On 8 August 2013 Long got his first call up to the England U21 team for the match against Scotland U21s on 13 August at Sheffield United's Bramall Lane. Upon his first call up to the U21s Long stated "It makes it a bit more special that it's at Bramall Lane. There will be a great atmosphere there and a packed stadium, so I'm looking forward to it." On 27 August 2013 Long was called up for the England U21s again under new boss Gareth Southgate for matches against Moldova U21s and Finland U21s for Group 1 2015 U-21 Euro Qualifier matches and once more in November for matches against San Marino U21s and Finland's U21s again.