Billionaire Li Ka-shing — one of the world's richest men — is set to retire on Thursday ahead of his 90th birthday later this year, capping a career as one of Asia's most storied businessmen and handing the reins of his corporate empire to his son.

Known as Asia's "superman," Li formally stepped down as chairman at the annual shareholders' meeting of CK Hutchison, his conglomerate with interests in real estate, telecommunications, shipping and retail. He was due to leave a similar position at property arm CK Asset Holdings later in the day at its meeting.

The move had been flagged as long ago as 2012 and the date was formally announced in March. It comes as a number of Asia's family-run businesses face leadership transitions.

"It's been a long succession process," Joseph Fan, a professor of accountancy and finance at the Chinese University of Hong Kong, told CNBC's "Squawk Box," adding that it has actually been more than 30 years in the making.

Li plans to stay on as a senior advisor, but his son, Victor Li, 53, will take over. And though the move has been widely telegraphed, analysts were still speculating on how the transition will play out given the size of the businesses.