"In his daily fight against violations of human rights and against injustice, arbitrariness, and authoritarianism, [Byalyatski] worked without respite so that the citizens of Belarus can one day enjoy European standards," Jean Claude Mignon, the chairman of the Parliamentary Assembly of the Council of Europe (PACE), said on September 30 in announcing the award in Strasbourg.
Byalyatski helped found Belarus's opposition Popular Front and heads the Vyasna (Spring) human rights group.
He was sentenced in November 2011 to 4 1/2 years in prison on tax-evasion charges that his supporters say were politically motivated.
The charges stemmed from Byalyatski's alleged use of personal accounts in Lithuania and Poland to receive funding from international donors for human rights activism in Belarus.
The U.S. State Department has called on the Belarusian authorities to immediately release Byalyatski and other political prisoners in the country.
Amnesty International has declared him a prisoner of conscience.
"This [prize] is an appreciation of the many years of his rights activism, his principled position, heroism, his openly standing up for human rights and freedom of his people, as well as of his love of Belarus," Byalyatski's wife, Natallya Pinchuk, said in accepting the prize on his behalf.
WATCH: Natallya Pinchuk accepts the prize.
"The fight against human rights violations, support of, and assistance for those who became victims in the struggle for democratic views are the inspiration behind the activities of the rights organization Vyasna he established in 1996. The degree, to which the activities of this organization had been hindering the authorities from lawlessness, can be judged by the ban on Vyasna's activities and multiple arrests of Ales; the last one, alas, being his long-term imprisonment that has been ongoing for over two years now."
The Vaclav Havel Prize rewards outstanding civil-society action in the defense of human rights in Europe and beyond.
It's awarded by PACE in partnership with the Vaclav Havel Library in Prague and the Czech Charter 77 Foundation. It is worth 60,000 euros ($81,000).
The three shortlisted nominees also included Georgia's Young Lawyers' Association and the Rights Defense Network of China.