Day, who announced her retirement from international rugby in October, beat off fierce competition from hockey player Nick Brothers, who represented England in both the Champions Challenge and European Cup in 2007, jockey Sam Waley who won four races against professional jockeys in 2007, runner Andrew Weir who became the first British runner over 40 years old to finish the Chicago Marathon and athlete Phil Wicks who was the fastest individual competitor in the Bloomberg Square Mile Relay.
Day last season led England to a second successive RBS 6 Nations Grand Slam title. She has also competed in three IRB Rugby World Cups, most recently in 2006 when England finished second to World Champions New Zealand.
Day said: “It's obviously a great honour to be given this award and I feel amazingly fortunate to have had the opportunities and experiences that I've had playing rugby for England over the years. I like to think that something like this represents a little bit of recognition for our sport and I hope that the talented players and team now developing within England women's rugby will get the recognition that they deserve over the next few years. I shall be enjoying my retirement and watching them from the comfort of the stands!"
Day, who plays rugby for Wasps, is a corporate finance manager for KPMG.