The transport group began operating services on its first rail contracts in Germany at the weekend, more than two years after winning the work.
The group will operate two lines on the Rhine Munster Express route, which serve the North Rhine-Westphalia region, including Cologne and Bonn.
National Express secured the contracts in February 2013. They will run for 15 year and will generate around £2.2bn in revenue.
Dean Finch, National Express chief executive, said: "Germany is Europe's largest rail market and is an important part of our strategy.
“I am delighted that after significant planning and preparation we have started running services.
“We will be implementing our approach and success in running the UK's best performing franchise, c2c, in Germany.”
He added: “The German rail market presents significant further opportunity for National Express. We are working on the start-up of our next two German rail contracts on the Rhine-Ruhr Express.
“These bring our already secured revenues from German rail to €2.6bn. We await the outcome of the appeal on the €1.4bn Nuremberg S-Bahn contract, have recently submitted a bid for another German rail contract and see an active pipeline of attractive opportunities throughout 2016.”
National Express has procured 34 new Bombardier Talent 2 EMU trains on behalf of the regional transport authorities to operate the new services.