The leases are both for 12 years and will be delivered to the airline straight from the factory.
Bombardier’s C Series the only new-technology single-aisle aircraft specifically designed to serve the 100-150 seat market, Avation said.
“The company is pleased to welcome airBaltic as an addition to the company's airline client base,” said executive chairman Jeff Chatfield.
“The company seeks long-term leases and these two 12-year leases align with our strategy. The company continues to diversify its aircraft portfolio and recognises the importance of new technology single-aisle aircraft such as the CS300.”
He added: “Avation has a view that the C Series joint venture with Airbus and Bombardier may increase sales volume of the programme.”
Avation shares edged 0.7% higher to 217p in early deals.