The royal pair received a welcome from the chancellor in Berlin on Monday at the beginning of their two-day visit.
They went on to a reception with full military honors and lunch with German President Joachim Gauck at the Bellevue Palace, before departing for appointments in the state of Hesse.
On Tuesday, the couple - and a delegation representing Dutch business - will continue on to Baden-Württemberg.
The visits to both Hesse and Baden-Württemberg had been planned ahead of Queen Beatrix's abdication. However, the itinerary was extended to include a first official visit to Berlin as head of state for Willem-Alexander. In both states, the royal pair were to meet German and Dutch entrepreneurs.
The schedule for the visit to the Hesse state capital of Wiesbaden included a reception with state premier Volker Bouffier. Also on the itinerary was a visit to a memorial to William the Silent, the founding ancestor of the Dutch royal family who had strong links with Hesse.
A visit to the Opel car factory at Rüsselsheim was planned for Tuesday, along with engagements near Stuttgart at machinery and laser firm Trumpf and the University of Hohenheim.
The 46-year-old king is the youngest monarch in Europe and is the first Dutch king in 123 years, since Willem III died in 1890.
rc/msh (AFP, dpa)