Prosecutors had asked the court for an eight-year term.
She was found guilty of illegal border crossing, carrying contraband, and fostering unrest with the help of foreign funding.
"Umida Niyazova should never have been arrested in the first place, and she should never have been tried on these politically motivated charges," Human Rights Watch official Rachel Denber told RFE/RL. "And we call on the Uzbek authorities to release her immediately."
"Umida's prosecution -- and the prosecution of 14 other human rights defenders who are currently in prison in Uzbekistan -- clearly demonstrates that the government wants to silence critical voices, that it is trying to clamp down rather than develop a civil society," she added.
Niyazova has 10 days to appeal the sentence. Her trial had three hearings since it began on April 19.
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