Several fans and pundits questioned the star's inclusion given his paucity of match action at the club level.
The 30-year-old defender from Manchester United earned his 59th cap for England in last night's 3-1 victory over Scotland after coming off the bench.
Despite the win, Maguire scored an own goal during the game which has led many fans to criticise the defenders' performance.
Maddison has now come out to support his England teammate on social media with a caption hailing the defender.
Maddison’s social media post
Fellow England star Maddison, who moved from Leicester to Tottenham this summer, responded to Maguires' criticism on social media.
According to the Sun, he shared a picture of himself talking to Maguire before the game and used the term "big" in the text, along with a number of ball emojis.
Maguire has faced a lot of criticism from fans and pundits after his performance against Ukraine and Scotland.
Scottish supporters yesterday at Hampden Stadium cheered his entry onto the field and jeered him at every touch.
Maguire's situation deteriorated further when he scored an own goal halfway through the second half, adding to the mounting pressure.
He is still an important player for Southgate, though, having been instrumental in the Three Lions' runs to the Euro 2020 final and the 2018 World Cup semifinal.
Southgate has jumped to Maguire's defence, calling the subsequent "ridiculous treatment" and criticism he received "a joke."