Yameen, the half-brother of the islands' long-time strongman ruler, was sworn in by the chief justice at a nationally televised ceremony attended by his defeated opponent Mohamed Nasheed.
The 54-year-old politician was accorded a 21-gun salute and in his first address to the nation pledged to work with neighbours and the international community which had put his nation of 350,000 Sunni Muslims on notice to elect a leader by Sunday or risk censure.
"We will maintain good neighbourly relations with regional countries and others," Yameen said.
"I shall strive to make Maldives the safest and most developed nation in the region.
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The United States and regional superpower India were among the first to congratulate him and said they looked forward to working closely with the new leader.
New Delhi had an uneasy relationship with Male after the toppling of former president Nasheed who once took refuge at the Indian High Commission in Male to avoid arrest while the US led international concern o