The court in Ganca sentenced Baxtiyar Haciyev (aka Bakhtiyar Hajiyev) for evading military service.
Haciyev, 29, told the judge in court that "you have a chance to show that this verdict [will not be] a political order. [However] I don't believe you will pass a fair decision."
Haciyev, a Harvard graduate and former parliament candidate, denied the charges and attributed his arrest to his Facebook activity trying to organize antigovernment protests.
Haciyev's lawyer said he was planning to appeal the verdict.
Haciyev's mother told RFE/RL the trial was in the spirit of Soviet dictator Josef Stalin's 1937 show trials. "From day one I was saying that it is still  in Azerbaijan.... Now I can see that it is even worse than '37."
Haciyev and his supporters launched the March 11 "Great People's Day" online event in which they asked people to click their approval of the protest, as well as to gather in different towns and cities across Azerbaijan.
He was arrested on March 4 and ordered held in pretrial detention for a month for violating an order not to leave Ganca while previous charges of evading military service were being investigated.
On May 12, the European Parliament condemned the crackdown on opposition protests in Azerbaijan and expressed "deep concern" at the increased number of attacks on civil society, social-network activists, and journalists in the country.
Isa Qambar, the chairman of the opposition Musavat Party, condemned Haciyev's conviction.
Qambar told RFE/RL the verdict "shows how afraid the authorities are of society becoming more active. This decision will only embarrass the Azerbaijani government in the eyes of its own people and in the international arena. The government should stop playing games and start real, serious reforms. And it should start by freeing journalists, youth activists, and opposition members from jails."
The U.S. Embassy in Baku said in a statement that the timing of Haciyev's arrest following his efforts to organize antigovernment protests "raised questions about [the] authorities' use of the judicial system to punish dissent."
It said the United States "firmly supports the strengthening of democratic institutions and the rule of law in Azerbaijan and calls upon judicial authorities to ensure Haciyev's appeals are reviewed in accordance with Azerbaijani law and international commitments."
Haciyev said during the trial -- which was monitored by Organization for Security and Cooperation in Europe observers -- that the reason he returned to Azerbaijan from the United States last year was because he thought "we had a chance to make some reforms."
European Parliament President Jerzy Buzek is scheduled to begin a visit to Azerbaijan on May 20.
Read more in Azeri here