Eddie Chu won his constituency with more than 80,000 votes - the most of any candidate in the polls.
A Hong Kong lawmaker advocating more autonomy from China who won a seat in landmark elections last weekend said today he had received "death threats" before and since the polls as he reported them to police.
Eddie Chu was one of at least five candidates in the semi-autonomous city pushing for more distance or even an outright break from Beijing who took seats for the first time in the Legislative Council assembly Sunday amid fears of China tightening its grip.
Chu, 38, is also an environmentalist who has campaigned against the destruction of heritage properties to make way for newer developments.
He said he was unable to go home because he was being stalked and the safety of his family threatened.
"I received death threats...because of my political views," Chu told reporters.
"The threat to my personal safety is imminent...it has drastically worsened in the past two to three days," he said before going into the city's Wan Chai police station with his lawyer.
He did not give any detail on who had made the threats and how they reached him.
Michael Vidler, a lawyer assisting Chu, urged police to take the case seriously.
"Politically motivated threats or violence against elected representatives of the people is a direct attack on the rule of law and democracy," Vidler told reporters.
"The Hong Kong police are duty bound to uphold the rule of law and everybody's constitutional rights, including Mr Chu's," he said.
Sunday's election saw a record turnout with more than two million residents casting their votes in the city of seven million.
It was the first major poll since the 2014 "Umbrella Movement" protests, with the anti-establishment camp increasing its share of the legislature, which is still weighted towards Beijing.
Chu, standing as an independent, emerged as winner in his constituency with more than 80,000 votes - the most of any candidate in the polls.
His allegations mark the latest controversy to hit the election.
Several pro-independence activists were banned from standing and two say they will now appeal their disqualification, according to media reports.
Pro-establishment candidate Ken Chow, of the Liberal Party, has also complained of interference, saying he was told to quit the race to make way for other pro-Beijing candidates.