The 30-year-old former Everton centre-back has passed a medical with the Bundesliga club and will play in the German top flight for the first time.
Heitinga was a free agent after leaving Fulham following their relegation from the Premier League last season.
The former Atletico Madrid man, who missed out on a place in the Netherlands' FIFA World Cup squad, signed a short-term contract with Fulham in January after falling out of favour at Everton.
Heitinga has made 87 appearances for his country and will bring vast experience to Jos Luhukay's Hertha squad.
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