YANGON—Myanmar appointed a naval chief, considered by some residents as a political moderate, to be one of the country’s two vice presidents, after a former pick made in July was apparently disqualified.

Vice Admiral Nyan Tun, 58, was sworn in early Wednesday, according to the Associated Press and is replacing former vice president Tin Aung Myint Oo, who resigned earlier this year for health reasons.

Myanmar officials had earlier named as vice president a former general named Myint Swe, who had served as chief minister of the Yangon region and as a general staff officer under former Myanmar strongman Than Shwe. But he was later passed over because one of his relatives is a foreign citizen, which disqualifies him for such a senior office under Myanmar laws, according to local media reports.

The vice president who resigned, Mr. Tin Aung Myint Oo, was considered a political hard-liner who resisted further reform in Myanmar, which has embraced wide-ranging political and economic changes since a new, nominally civilian government took power last year following decades of military rule.

Western nations including the U.S. have eased sanctions against Myanmar since the new government took over, but they still maintain some restrictions on the country as they wait to see if there is further reform. Many foreign leaders have been watching closely to see who would replace Mr. Tin Aung Myint Oo, and whether it would be a figure considered to be more in line with Myanmar President Thein Sein’s reformist tendencies.

Mr. Nyan Tun has been Myanmar’s naval commander since 2008, and he also served briefly in the country’s military intelligence in the 1980s. Residents in Yangon on Wednesday said the new vice president did not have a reputation of deep involvement in the alleged human-rights violations of Myanmar’s former military regime, though details remained hard to come by.

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Mr. Nyan Tun was nominated by military lawmakers, who make up 25% of the country’s legislature and have the right to choose one of the country’s two vice presidents. The other vice president, Sai Mauk Hkam, comes from Myanmar’s large Shan ethnic minority but is not widely believed to hold extensive power.

National Assembly speaker Khin Aung Myint announced the appointment during a legislative session in the capital, Naypyitaw, and Mr. Nyan Tun was sworn in shortly afterward, the AP said.

Write to Patrick Barta at patrick.barta@wsj.com