The 26-year-old joined Hertha from Bayern Munich in 2011, and started every game as the club were relegated from the Bundesliga in his first season.
They immediately bounced back as second-tier champions, however, with Kraft maintaining his position as a regular first choice.
On Monday, the club announced the keeper was now contracted until June 2017, with sporting director Michael Preetz delighted to have tied the German down.
"Thomas Kraft is an absolute top performer in our team," he said.
"Both as a goalkeeper and as a person he is very important for the team."
Kraft himself added: "I feel comfortable with Hertha Berlin and I am sure that we will see even more successful years together."