OSLO - Mr. Abiy Ahmed, the prime minister of Ethiopia, spearheaded a peace accord in his region and catalyzed reforms at home.

Abiy Ahmed, the prime minister of Ethiopia, was awarded the Nobel Peace Prize on Friday, for his work in restarting peace talks with neighboring Eritrea, ending a long stalemate between the two countries.

Mr. Abiy, 43, broke through two decades of frozen conflict between his vast country, Africa’s second most populous, and Eritrea, its small and isolated neighbor. When he became prime minister of Ethiopia in 2018, he made it clear that he wished to resume the stalled peace process, doing so in close cooperation with President Isaias Afwerki of Eritrea.

The two nations share deep ethnic and cultural ties, but until July last year they had been locked into a state of neither peace nor war, a conflict that had separated families, complicated geopolitics and cost the lives of more than 80,000 people during two years of border violence.

In its official announcement, the Nobel Committee detailed a litany of accomplishments for Mr. Abiy in his first 100 days as prime minister: lifting the country’s state of emergency, granting amnesty to thousands of political prisoners, discontinuing media censorship, legalizing outlawed opposition groups, dismissing military and civilian leaders suspected of corruption, and increasing the influence of women in political and community life.