Muller, 31, and Hummels, 32, are both included having been told by Low that their international careers were over in March 2019. He moved the duo aside, along with Jerome Boateng, in an overhaul of the national squad as he prioritised the next generation. But both Muller and Hummels' club form for Bayern Munich and Borussia Dortmund respectively has persuaded Low to bring them back into the squad.
While Muller and Hummels both earn recalls, there is no place in the squad for Paris Saint-Germain midfielder Julian Draxler, Bayern's Boateng or Dortmund's Julian Brandt. Bayer Leverkusen defender Jonathan Tah also misses out while Barcelona goalkeeper Marc-Andre ter Stegen is absent through injury and Marco Reus announced he was unavailable for selection on Tuesday following a "complicated" and "exhausting" season.
Low, who will leave his post as Germany manager after the Euros, unveiled the 26-man squad on Wednesday and included 18-year-old forward Jamal Musiala. Kevin Volland and Robin Koch were also surprise inclusions, as Low aims to finish his time in charge of Germany on a high.
Low said the recall of Hummels was made with "absolute conviction" after his form for Dortmund, and he hopes the 32-year-old will bring leadership and stability to the defence.
"He has played a few tournaments and knows how to manage difficult moments," Low said of Hummels.
Germany failed to get out of the group stages at the 2018 World Cup which prompted Low to move Muller, Boateng and Hummels aside in an attempt to give the next generation a chance to impress for the national team. But Low said "the development had not progressed as well as we wanted," which has led to the return of Muller and Hummels.
The Germany manager said he did not regret jettisoning Hummels and Muller in 2019, but said they had to "rethink" that policy of favouring youth, with success in this tournament important "above all else."
Muller has impressed for Bundesliga champions Bayern, and has scored 11 goals this season in the German top flight, alongside 21 assists.
Regarding his decision to pick AS Monaco striker Volland, Low said: "We have seen what he has achieved in France this season, he is assertive. With his strong physique and his eye for goal, he can certainly benefit us."
Low also called Ter Stegen's unavailability due to knee surgery "very regrettable," while he said Boateng's exclusion in "no way diminishes our opinion of him" and that he appreciated Reus' sincerity regarding his decision to rule himself out of the tournament.
"Marco and I, we had a very open conversation," Low said. "He called me. I have known him for many years. Unfortunately, he always had the bad luck that he sustained a few injuries and was cancelled.
"It sometimes left its mark on Marco. He is a great footballer. He is a win for any team and was in good form. But he also told me that it was an energetic achievement for him and that he is a bit tired. And he told me frankly that it would be good for his body to take a break now.
"And I said:'We need a lot of energy!' When we go to the training camp, things really start. I have to thank him for his frank words. He is a great footballer and we would have loved to have had him with us."
Defenders: Matthias Ginter (Borussia Monchengladbach), Robin Gosens (Atalanta), Christian Gunter (SC Freiburg), Marcel Halstenberg (RB Leipzig), Mats Hummels (Borussia Dortmund), Lukas Klostermann (RB Leipzig), Robin Koch (Leeds United), Antonio Rudiger (Chelsea), Niklas Sule (FC Bayern)
Midfielders/Attackers: Emre Can (Borussia Dortmund), Serge Gnabry, Leon Goretzka (both FC Bayern), Ilkay Gündogan (Manchester City), Kai Havertz (Chelsea), Jonas Hofmann (Borussia Monchengladbach), Joshua Kimmich (FC Bayern), Toni Kroos (Real Madrid), Thomas Muller, Jamal Musiala (both FC Bayern), Florian Neuhaus (Borussia Monchengladbach), Leroy Sane (FC Bayern), Kevin Volland (AS Monaco), Timo Werner (Chelsea)