Kuwait's appeals court on Sunday slapped the jail term on former member of the Kuwaiti parliament, Mussallam al-Barrak, his nationalist Popular Action Movement (PAM) said.
"You can jail my body but not my ideas and will,” PAM quoted Barrack as saying, adding that the campaign for reform in the oil-rich nation would continue.
The ex-MP was arrested on charges related to a speech he gave to tens of thousands of people in October 2012, in which he criticized changes to the electoral law. Barrak had said that the new law allows the ruling Al Sabah family to manipulate the outcome of elections.
He was initially sentenced by a lower court to five years in jail in April 2013.
In July last year, Barrak was arrested on separate charges of insulting the judiciary.
He was questioned over so-called offensive remarks he made at a June 10 public rally, in which he said former senior officials including members of the ruling family took tens of billions of dollars from public funds and engaged in money laundering.
The Persian Gulf nation was the first Arab state to establish an elected parliament in 1962. However, the Al Sabah family remained in control of most key posts, including the premiership and the ministries of defense, interior, and foreign affairs.
Human Rights Watch has criticized the Kuwaiti government for its crackdown on activists and protesters over the last three years. The regime tightened its curb on dissent after sporadic protests erupted in the country in 2012.