The campaign launches this weekend across print, online and outdoor media and is being handled by New York agency McGarryBowen.
Online activity includes an audio message from Khan at and the boxer, who won silver in the last Olympic Games before turning professional, will also wear Reebok gloves, kit and boots for all of his fights as part of the deal.
This latest campaign features Khan showing his sensitive side, with posters featuring the quote, "seeing your opponent on the canvas is the greatest thing... but then I start to worry about what I may have done to him".
Khan, who is the first boxer to sign up to the 'I Am What I Am' campaign, said: "I used to look up to sports stars such as Imran Khan and now it's going to be me on the billboard. I'm giving Asian kids out there a path to follow."
Khan's link-up with Reebok follows his victory over Cuban boxer Mario Kindelan at the Reebok Stadium, home of his local football team Bolton Wanderers.
Michael Price, Reebok UK marketing director, said: "This is a really exciting partnership for Reebok and Amir Khan. It's great to sign someone from Reebok's hometown."
Andy Towne, Reebok's European marketing vice-president, added: "The 'I Am What I Am' campaign is intended to inspire young people to find their own voice by celebrating contemporary icons. Amir's passion, success and unique talent along with his position as a real modern role model makes him an ideal ambassador for us."
The Mike Skinner creative last September was the most recent outing for the 'I Am What I Am' campaign in the UK. Others have included the actress Lucy Liu and controversially the rapper 50 Cent, whose ad was withdrawn by Reebok after complaints regarding glamorisation of gun culture.
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