It continued a fine tournament for Maguire, who missed the first two group games as he recovered from ankle ligament damage.
With a semi-final against Denmark at Wembley on Wednesday night, Maguire’s season could yet end in European Championship glory.
That seemed a long way off after he was handed a suspended jail term in Greece following an altercation on the island of Mykonos last summer.
Despite the sentence on 25 August – which was appealed by Maguire’s legal team – Southgate included the defender in his England squad that day, although he ultimately had to drop the 28-year-old.
“Gareth’s support of me has been brilliant ever since I made my debut for England,” said Maguire.
“He picked me to make my debut and then I think ever since I’ve been available I’ve pretty much played in every game possible. That gives me great confidence and belief and trust going into the game to enable me to perform to my best.
“I wouldn’t say any specific moments, there’s numerous of them. Lots of conversations, lots of texts, lots of phone calls. And then speaking to him when I’ve come into camp he’s always there to help.
“It’s part and parcel of being a footballer, the ups and downs. I’ve spoken about it. It’s impossible to go through a career without having bad moments, mistakes. He can pass on his experiences and the way he handles things and I’m always open to learn and improve.”
Maguire also insists he had no concerns over his England future following the incident, adding: “I never feared for my international career.
“I always felt like I had something to bring and something to offer. And I knew without going into too much detail about what went off in the summer.
“I knew where I stood on behalf of that. So, I always knew what went off and I’m totally over it now. I’ve moved on. It was a tough time for sure but I’ve moved on.”
Southgate named Maguire in his 26-man squad for the Euros despite an ankle injury ruling him out of the end of the season for Manchester United – including missing the Europa League final defeat to Villarreal.
“With any injury you don’t know how you’re going to recover, you don’t know the rehab, you don’t know whether you’re going to have a setback,” he said.
“Touch wood I haven’t had any setbacks in my rehab at the moment. It’s all gone smoothly, it’s all gone to plan and it’s all gone probably a bit quicker than we all thought.
“To miss the Europa League final was disappointing and then I fully set my sights on making the Euros squad.
“I didn’t know which game at that moment when I would be available or when I would be able to play football at such a high competitive level, it’s not like I’m getting thrown into a friendly match, it’s the European Championship, it’s so demanding.”
With Southgate’s current contract running until after the 2022 World Cup in Qatar, Football Association chief executive Mark Bullingham has revealed they want to extend the deal – something Maguire backs.
“Yes, of course,” he replied when asked if the players wanted Southgate to sign fresh terms.
“I can only speak on behalf of myself but I’m sure everyone as well is so happy in terms of coming to the England camps and the way that he has made it so enjoyable for everyone.
“Obviously winning football matches over the last three years has really helped that along as well.
“I can’t speak highly enough of Gareth, what he’s done for myself personally and the trust and faith he has put in me.”