Former Olympic and world 400 metres champion Christine Ohuruogu admitted it is the right time to quit after announcing her retirement.
The 34-year-old won Olympic gold at Beijing 2008 and silver in London four years later.
She also claimed world titles in 2007 and 2013, but her last major medal came two years ago, with 4x400m bronze at the Rio Olympics.
Ohuruogu, who is halfway through a law degree at university, said in a statement on her website: "Today is the start of the British Championships and, as I won't be there competing, I feel it is a good time to formally announce my retirement from competitive athletics.
"I didn't feel ready to retire after last season but a combination of my studies and a niggling injury restricted how much training I was able to do this year.
"I end my career with four Olympic medals and five World Championships medals.
"Athletics has been my passion for so long and I am proud to call myself an athlete."
Ohuruogu served a 12-month ban from athletics for missing three out-of-competition drugs tests between October 2005 and July 2006, returning just in time to clinch her first outdoor world crown in Osaka in 2007.
A British Olympic Association bylaw meant all doping offences were punishable by lifetime Olympic bans, however, putting her participation in Beijing in doubt.
She appealed to the Court of Arbitration for Sport, which upheld the suspension but said it believed it was just a case of her being forgetful when the testers arrived. The ban was eventually lifted in November 2007.
The London-born Newham & Essex Beagles club member took up athletics in 2001 in a bid to boost her netball skills.
"I love the diversity of the events and the brilliant characters that come from them," she added.
"I have truly met some wonderful people over the last 15 years, competing around the world, and I am blessed to call many of them friends."