The sentences Thursday were the latest in an intensified crackdown against dissent in the one-party, authoritarian state.
Lawyer Nguyen Thanh Luong says Nguyen Phuong Uyen was sentenced to six years, while Dinh Nguyen Kha received eight years after a one-day trial.
They were arrested in October in Ho Chi Minh city for handing out leaflets urging protests against China's territorial claims in the South China Sea.
Popular anger against China puts Hanoi in a difficult position because it can't afford to alienate Beijing, its large, fellow Communist neighbor.
Luong said the two meant to demonstrate "patriotism and did not mean to oppose the government."