Nagelsmann admits Thiaw's form with Newcastle United in his first season in the Premier League has warranted his selection.
Thiaw so far has three caps and this week can put himself in front of Nagelsmann ahead of next year's World Cup planning.
The coach said, "Malick has stabilised and is doing very well as a regular starter at Newcastle.
"He was absent from our squad for a long time, partly because he hadn't played much in Milan for six months prior. He deserves to be back."
Nagelsmann added: "We need a good balance within the team. We want to have two players for every position, so the structure has to be right.
"We are convinced that we have the right players to get six points from the two games and qualify for the World Cup. That's the most important thing."
Germany meet Luxembourg and Slovakia in their final World Cup qualifiers.