The 27-year-old Pearson, who won 100 metres hurdles gold at the London Games, was runner-up to American Brianna Rollins at this year's world championships in Moscow in defence of her 2011 title.
"The time is right for us to go our separate ways," Pearson said in a statement on Athletics Australia's website (www.athletics.com.au) on Wednesday.
"Sharon has made me into a champion but I feel that to move to another level I need to freshen up my approach to training, develop fresh ideas and incorporate new challenges into the way I do business.
"My competitors are always striving to make themselves better and I must do the same."
Pearson would investigate her coaching options with Athletics Australia and make an announcement in the near future, the statement said.
Hannan said: "Yes I am disappointed, but Sally and I discussed the options and she believes this is best for her.
"We had some amazing performances. We have conquered the world and I wish her every success for the future and hope that she continues to conquer the world."
A self-taught coach, Hannan first spotted Pearson as a young girl at a regional junior championship in Australia's northeastern Queensland state and guided her to a silver medal in the 100m hurdles at the 2008 Beijing Olympics.
The partnership survived the years despite criticism from specialist coaches and officials in Australia's athletics community.
"My coach has always believed in me more than I've believed in myself, and she pulled me through even with all the doubters that didn't believe in us or her coaching strategies," Pearson told Reuters in an interview in the leadup to London.
After taking a break following her London triumph, Pearson returned to training to defend her world title in Moscow in August but suffered two hamstring injuries in the lead-up before being upset by Rollins.
Pearson said she was satisfied with the result but later told Australian media "silver's not going to happen again".
- Sports & Recreation
- Athletics Australia
- Brianna Rollins