Lien has kept the local news media guessing about his intentions to run for mayor since last year. The post is seen as a political proving ground for the presidency, as it is the route that former presidents Lee Teng-hui, Chen Shui-bian and the incumbent, Ma Ying-jeou, all took.

"I had to make sure I am healthy enough for this important job, that was why I had to wait for the entire report of my health check to be ready, and that came out only recently," he told a packed news conference.

Lien is popular within the KMT, especially with the younger generation, and has been tipped to win the mayor's race. But he will still have to take part in the KMT primary, which will pit him against at last three hopefuls - all incumbent legislators - to become the KMT nominee for the mayoral race.

Most opinion surveys show that Lien is by far the most likely to win, leading Ko Wen-je, an independent but popular physician at National Taiwan University Hospital. Ko was part of the medical team that saved Lien's life after the 2010 gun attack that saw a bullet pierce Lien's head and exit through his face.

So far, the main opposition Democratic Progressive Party has yet to select a candidate for the election or hold any primary to decide its nominee.

But pundits said Lien's billionaire family and his father's close ties with the mainland would make him a ready target for his opponents.

"I can't choose my parents," Lien said, adding that he would donate his entire salary to charity if he won the race.

Lien's father Lien Chan, who was a former vice-president, made history in 2005 after his fence-mending visit to Beijing as KMT head. Lien Chan met then Communist Party general secretary Hu Jintao to discuss reconciliation between the two former rivals.

The mainland and Taiwan had been hostile since 1949, but they have grown closer since 2008, when Ma became president and began engaging Beijing.