TAIPEI, Taiwan — President Ma Ying-jeou was re-elected by a comfortable margin on Saturday, fending off a challenge from his main rival, Tsai Ing-wen, who criticized his handling of the economy but also sought to exploit fears among voters that Mr. Ma’s conciliatory approach toward China was eroding the island’s sovereignty.

Mr. Ma’s victory was welcomed by Taiwanese business leaders, who feared his defeat could irritate China and set back the détente that has served them well during the past three and a half years. China, which regards Taiwan as a renegade territory, had warned that a win by Ms. Tsai, whose party has traditionally backed formal independence, could threaten the “peaceful development of cross-strait ties.”

Recent polls had suggested the race would be very close, raising anxiety among those who prefer the status quo. That group included some American officials, who expressed unease in private that a win by Ms. Tsai could complicate the already difficult relations between China and the United States, a longtime ally of Taiwan.

Pursuing closer ties with China — and the money that flowed to manufacturers, hotel owners and farmers with new trade and transportation deals — helped solidify Mr. Ma’s support despite withering attacks from Ms. Tsai. More than 200,000 of Taiwan’s citizens who live and work across the Taiwan Strait in China flew home to vote, most of them taking the direct flights that Mr. Ma helped establish. Not surprisingly, many returnees were Ma supporters spurred by the polls that had showed him in a close race.