The country's ESTCube-1 satellite was launched, along with two other satellites, atop a European Vega rocket from the Guiana Space Center on South America's northeast coast, China's Xinhua News Agency reported.
Estonia's modest 2.2-pound satellite was joined in orbit by satellites deployed by Europe and Vietnam.
Estonia is now a "tiny space country," Estonian Speaker of Parliament Ene Ergma, an astrophysicist by training who was in French Guiana to observe the launch, said, but "it's really a big deal in my opinion."
University students in Estonia had been developing the ESTCube-1 nano-satellite since 2008 to carry out innovative solar wind experiments.
"I am very proud to be seeing all these students here who are watching their handiwork of five years," project senior researcher Mart Noorma said.