Barra said in a statement today that the steps were a "clear sign" of GM's commitment to its European subsidiary.
The company will put new money into engine and transmission production at plants in Ruesselsheim and Kaiserslautern in Germany and at Tychy in Poland.
A third shift will be added at the company's plant in Eisenach.
On a visit to Germany, Barra said the company plans by the end of the decade to build a new SUV model at Ruesselsheim that would serve as the Opel brand's "second flagship" along with its Insignia model.
SUVs have been one growth segment in Europe's depressed auto market.
General Motors' European business lost USD 387 million in the third quarter, half of which was restructuring costs. Opel is rolling out 27 new models and 17 new engines over the coming years in an attempt to become profitable.
Detroit-based GM as a group made USD 1.4 billion in net income in the third quarter.