Borussia Dortmund defender Hummels, a 2014 World Cup winner, returns to the squad for the first time since he played 90 minutes in Germany's last 16 defeat by England at the European Championship in 2021.
The 36-year-old Nagelsmann, the second youngest national team coach in their history, signed a contract until the end of July 2024. His assistants will be Sandro Wagner and Benjamin Glueck.
Neuer was ruled out for the rest of the season after undergoing surgery on a broken bone following a skiing accident.
Bayern Munich's four-game winless run -- their longest in the Bundesliga in 20 years -- has soured the mood among club bosses and piled pressure on coach Julian Nagelsmann to quickly turn things around.
Pavard will miss this weekend's opening game of the Bundesliga season at Borussia Moenchengladbach with an injury.
Haaland has scored 37 goals in 38 games for Dortmund this season in all competitions.
Despite missing a month with injury, Haaland, 20, has managed 17 league goals this season, but admits there is "a lot" he can learn from Lewandowski
Nagelsmann is already the toast of European coaching after becoming the youngest manager to reach the Champions League semi-finals.