Professor Gratton is a leading thinker on the role of people in organisations and has "consistently led" debates on the future of the workplace, organisers said.
Each year HR Magazine compiles the HR Most Influential ranking, a definitive list of directors and thinkers who have the biggest impact in the area of people strategy.
The ranking was unveiled at a glittering event at Claridge's in central London in September.
Gratton, who first appeared in the first HR Most Influential ranking eight years ago, said: "I know everybody has related to HR at some point in their career and it's a marvellous time to be an HR person. And it's become very clear to me that human capital sits at the very heart of everything in the workplace."
The ranking is selected through a painstaking process, beginning with a long-list of hundreds of names made up of people nominated by HR Magazine readers which is then scrutinised by an expert panel of HR directors and leading academics.
Gratton's most recent book is The Shift, an exploration of the rapid changes taking place in the way people work. In 2011 she was ranked by the Times as one of the top 15 business thinkers in the world.