Currently editor of the Saturday edition of the paper, Freeland will take up her new role in July, when Ridding moves to Hong Kong to become editor and publisher of the Financial Times in Asia.
Meanwhile, Richard Addis, who is currently the FT's design editor, takes Freeland's place on the Saturday edition, although he will retain his design brief.
Freeland, who is seen as a rising star at the paper, joined in 1994, filling the positions of Eastern Europe correspondent, Moscow bureau chief and then UK news editor, before returning to her native Canada to become deputy editor of The Globe & Mail.
She returned to the FT in October 2001 as editor of FT.com, launching the website's subscription services in May 2002.
FT editor Andrew Gowers praised what he called her 'strategic sense, combined with an incredible ability to get things done'.
He also credited Addis as being a 'key player in driving the changes we've made to the daily and Saturday editions of the paper. He is ideally placed to take the baton from Chrystia'.
In a week of senior moves at the FT, Andrew Hill has been made comment and analysis editor. Hill, who is the paper's current New York bureau chief, will return to London to take up the post. He is replacing John Gapper, who has been made chief business commentator and associate editor.
Gowers said of Hill: 'He has huge experience of business in the UK, Europe and the US, and is the right person to take our comment and analysis pages forward.'
He added that, with Ridding's move to Hong Kong, 'we will have a global editorial operation to match our ambitions'.
The FT is printed in 20 cities worldwide, has a daily circulation of more than 460,000 and claims a readership of more than 1.6 million people.