The 29-year-old, who bats at number three in the Indian side, averages over 51 from 48 Tests for India and has scored 11 hundreds.
He was, however, ignored for the ongoing tenth edition of the Indian Premier League, and will be available to play in four county championship matches.
"I'm ready for it. I'm already working on my skills and preparing for competitive cricket," added Pujara.
"I love playing county cricket
Nottinghamshire are at the top of the table in Division Two, with three wins from three matches and Pattinson taking 20 wickets.
"We have looked around the world to find the right player," Mick Newell, Nottinghamshire director of cricket, said in a statement.
"The most important thing was to sign someone with the quality to make us better, rather than limiting our options by saying it had to be a bowler.
"We have depth in our squad with regards to bowling and - particularly as we'll be without Alex Hales during that period - we're more than happy to welcome a world-class batsman to the Club."