Featuring Entourage star Jeremy Piven, Zoe Tapper and Katherine Kelly, the show tells the story of Harry Gordon Selfridge, the founder of Selfridges department store.
The second series, which will once again be written by Andrew Davies and his team, will move the story forward to 1914 and the lead-up to World War 1.
Series one of Mr Selfridge is currently midway through its run and has been edging out BBC One's rival period drama Ripper Street in the ratings. However, it hasn't quite matched the figures of BBC One's Call The Midwife.
It is ITV's most-watched new drama since Scott and Bailey launched in 2011.
Steve November, ITV's acting director of drama commissioning, said: "It is ITV drama at its best and we are looking forward to spending more time with the wonderful characters."
The director of episodes 5, 6 and 7 of series one, Anthony Byrne (Silent Witness, Single Handed), will return to direct the first of the new episodes.
Kate Lewis, exec producer for ITV Studios, said: "ITV Studios is thrilled to be making a second series of Mr Selfridge. The story of Harry Selfridge, his family and colleagues has drawn in a strong drama audience and we are delighted by the response. The second series will allow us to build on this success and it is a fantastic opportunity to focus on 1914 during the centenary of the Great War."
Watch a preview of Mr Selfridge below: