Klinsmann replaces Ante Covic, who only took charge in July after six years coaching the reserves, but was sacked following Sunday's 4-0 thrashing at mid-table Augsburg, the club's fourth straight league defeat.
Klinsmann, the 55-year-old a former European and world champion, was appointed to the club's supervisory board at the start of November, but steps in with Hertha just above the relegation zone.
“It's an honour to be able to help out,” said Klinsmann in a hastily arranged press conference.
“My father was an enthusiastic Hertha fan and my son played here for two years, so I know a lot of people here,” added Klinsmann.
Klinsmann's backroom staff also has plenty of experience.
His assistant coach Alexander Nouri helped rescue Werder Bremen from relegation in 2016-17, while goalkeeping coach Andreas Koepke won the Euro '96 title alongside Klinsmann for Germany.
Klinsmann's main task is to keep Hertha up. The club spent 2010-11 and 2012-13 in the second division.
Klinsmann, a California resident, was born in southwest Germany and started his career at Stuttgart, but he has held membership of Hertha for years and his father was a keen supporter of the west Berlin club.
Klinsmann in Hamburg in September. Photo: DPA
His son Jonathan played for Hertha as reserve goalkeeper from 2017 until the start of this season, when the United States Under-23 international joined Swiss side St Gallen.
“Berlin, as many people say, is a sleeping giant, but the situation is difficult, you can see that on the league table.”
Klinsmann confirmed he will be interim boss until next May to allow director of sport Michael Preetz time to find a permanent head coach.
“You have to be flexible, open and direct, it is foreseen that I will do this job until May 2020 to give Michael time,” explained Klinsmann.
“I don't know what is planned for May, but that's football.”
The former Tottenham, Bayern Munich and Inter Milan striker helped his country win the 1990 World Cup and 1996 European championships, making 108 appearances and scoring 47 goals for Germany.
He was then head coach of Germany from 2004 until the 2006 World Cup, when the hosts reached the semi-finals under his stewardship.
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He also led the United States national team from 2011 until 2016, guiding them to the last 16 of the 2014 World Cup finals in Brazil.
Hertha's director of sport Preetz described Klinsmann as a “successful, charismatic” coach “with radiant energy. A football expert”.
However, there are questions whether Klinsmann can be successful in the Bundesliga, a decade after Bayern Munich sacked him after just nine months and 43 games in April 2009.
He acknowledges the challenge he is facing.
“Coaching a national and a club team is something completely different, in a national team you have a lot more time,” he admitted.
Klinsmann's first game in charge of Hertha will be Saturday's home game against Borussia Dortmund at Berlin's Olympic Stadium.
He confirmed reports that ex-Germany defender and Hertha captain Arne Friedrich will be give a role as performance manager.
“He will have an open ear for the players and also help with their career planning,” said Klinsmann.