Thousands of fans from across the world cast their votes as the 21-year-old beat second-placed Brazil forward Marta and third-placed Canada captain Christine Sinclair.
The other nominees on the five-player shortlist for the BBC World Service award were Sweden keeper Hedvig Lindahl and Germany’s Melanie Behringer.
“Wow, it’s a surprise,” said Hegerberg.
“It’s a huge honour to win, with such big-name footballers nominated,” added the striker, whose club will seek to retain their Champions League title – to complete back-to-back trebles – when they face Paris St-Germain in Thursday’s all-French final in Cardiff.
“It’s really special, so many people from different cultures and countries voting for this trophy, it’s a huge motivation in itself.”
An emotional Hegerberg was presented with the award by her sister Andrine, a midfielder for Birmingham City and Norway, in front of her Olympique Lyonnais team-mates in France.
“She [Andrine] has been so important for me through my career, we’ve been supporting and pushing each other and my success is all for the both of us,” she said.
“She’s my best friend and really, I’m totally blown away.”
The award follows a glittering year for the striker, who played a big part in her French club’s treble-winning season in 2016 with 33 league goals and 13 Champions League goals.
She scored the opener in last year’s Champions League final against German side Wolfsburg and achieved her dream of lifting the trophy when they won 4-3 on penalties, adding the European crown to their Coupe de France and Division 1 titles.
And she was the only player to score more goals than Cristiano Ronaldo in Uefa competitions in 2016, netting 18 compared to the Real Madrid and Portugal forward’s 17.
She is close to repeating last year’s success this term as Lyon have already sealed the French league title and the cup – with Hegerberg scoring the winning penalty in the shootout against Paris St-Germain in this month’s final.
But it is the Champions League victory that really made a big impression on her.
“It’s the most important thing you can win in football, the highest trophy at club level. Winning it was such a fantastic feeling, a much bigger feeling than I thought it would be,” she said.
“I dreamed of it as a little kid, it’s a huge challenge and we showed we were capable of doing it.”
Her sister Andrine, who has played alongside her sister at clubs in Norway and Germany and also at international level, said Hegerberg’s winning mentality is one of the things that makes her special.
“She can score from any position on the pitch,” Andrine, 23, said. “It’s always dangerous when she has the ball.”
Hegerberg is the third winner of this BBC World Service award, following Nigeria forward Asisat Oshoala in 2015 and Scotland midfielder Kim Little in 2016.
Brazil captain Marta, nominated for a second time, was second in the vote after leading her country to fourth place at their home Olympics at Rio 2016, while Canada captain Sinclair was third following back-to-back Olympic bronze medals