She has been the 500 metre track time trial world champion on four occasions, and a gold medallist at the Commonwealth and Olympic Games. At the 2015 UCI Track Cycling World Championships Meares took the gold in the keirin—her 11th world title in total, which made her the most decorated female track cyclist of all time.
She was the flag-bearer and captain for the Australian team at the 2016 Summer Olympics, where she won a bronze medal in keirin. This made her the first Australian to win individual medals in four consecutive Olympics.
On 16 October 2016 Meares announced her official retirement from her current competitive cycling career.
Anna Meares started competitive cycling at the age of 11 in 1994, following her older sister Kerrie Meares into the sport. The family were inspired to take up competitive cycling by Kathy Watt winning a cycling gold medal at the 1994 Commonwealth Games. With the family living in the small Queensland coal-mining town of Middlemount, it was more than two hours drive to the nearest cycling track at Mackay for the girls to train.
In 2002 Meares narrowly missed a bronze medal in the inaugural inclusion of the 500-metre time trial at the 2002 Commonwealth Games in Manchester, while her older sister, Kerrie Meares won the gold medal in the event. She won a bronze medal in the sprint.
During the 2004 Olympic Games in Athens, she won a gold medal, and set a new world record in the Women's 500-metre time trial of 33.952 seconds. Meares had to beat a new Olympic record set just minutes previously by the reigning World Record holder, Yonghua Jiang of China. (See Cycling at the 2004 Summer Olympics). The event was abolished from the Olympic program so Meares could not defend her title in 2008. Meares also won a bronze medal in the Women's 200m Sprint event in Athens.
In May 2004 at the Time Trial World Titles in Melbourne Meares claimed the title of Women's World time trial champion, and won a silver for the sprint event. Also claimed first in the 2004 World Cup Time Trial in Sydney.
In 2005, Meares enrolled in a Bachelor of Learning Design course at Central Queensland University, but deferred her studies to concentrate on sport.
Meares made an astonishing come back from a very bad cycling accident at the World Cup in January 2008 when she broke her neck. Meares crashed in the third round of the World Cup circuit in Los Angeles in January 2008, seven months out from the Olympics. Meares fractured her C2 vertebra, dislocated her right shoulder, suffered torn ligaments and tendons, a heavily bruised right hip and skin abrasions as a result of skin sliding on wood when she crashed at 65 km/h. Astonishingly she was back on the bike just 10 days after the fall and went through intensive rehabilitation. With the points Meares had secured prior to the crash, she was able to fight her way back and qualify for the 2008 Beijing Olympics.
Meares had an eventful semi-final in the sprint at the 2008 Summer Olympics. Having lost the first heat to her opponent Guo Shuang, she won the second heat. The third heat saw Guo come down the banking too steeply and her front wheel slipped from beneath her. The heat was re-run and although Guo won by a few millimetres, she was relegated for coming down the track and pushing Meares onto the côte d'azure on the final lap. This put Meares through to the final ride-off for gold against Victoria Pendleton, where she was beaten and received the silver medal.
At the 2012 World Championships which took place in Meares' home country of Australia in Melbourne, Meares was favourite for three gold medals. In the team sprint Meares won silver as Germany set two world records in the event. In qualification for the individual sprint Meares broke the world record for the flying start 200 metres. Meares completed her four laps in just 10.782 seconds shaving 11 thousands of a second off Simona Krupeckaite's mark. In the semi final Meares faced her old rival Pendleton. Pendleton clashed with the Australian in their first heat and ended up on the floor before Meares was relegated from the second for going outside of her lane. In the decider Pendleton won in a photo finish, with Meares settling for bronze after defeating Lyubov Shulika. In the keirin, Meares won both her qualifying races before reaching the final, where she held off Russian Ekaterina Gnidenko and German Kristina Vogel to win the first of two world championships in Melbourne. Meares set her second world record of the championships in her final event. Meares recorded 33.010 seconds to break the record by .286 of a second which was previously held by Simona Krupeckaite. With the time Meares won her second title of the championships and equaled Felicia Ballanger's record of ten world titles.
At the 2012 London Olympics, Meares qualified for the final of the sprint, where she again faced Victoria Pendleton. In the first sprint of the final, Pendleton crossed the line first, but was relegated after illegally moving off her line as the cyclists sped through the final banking. Meares won the second sprint to win 2–0 and take the gold medal. She also won a bronze medal with Kaarle McCulloch in the team sprint.
Meares took rest after the 2012 Olympics and skipped the 2013 World Championship. She returned to competitions in July 2013. Later that year she set a new world record of 32.836 seconds in the women's 500 m time trial at the UCI Mexico Track World Cup, making her the first woman to go under 33 seconds in the event.
Meares was married for nine years to Mark Chadwick. They separated early in 2015. However, in late February that year she competed at the world championships and won three medals.
At the 2016 Rio Olympics Meares took part in three events. She won a bronze medal in the keirin, placing tenth in the individual sprint and fourth in the team sprint.
In 2001 Meares was awarded the Australian Junior Women's Track Cyclist of the Year. She was voted Australian Institute of Sport (AIS) Athlete of the Year in 2007 and 2011 and 2011 inducted into the AIS 'Best of the Best'. Between 2004 and 2012 she has been named Australian Elite Female Track Cyclist of the Year seven times, she also became Australian Cyclist of the Year in 2008 and 2012. She served as the Australian flag bearer at the opening ceremony of the 2014 Commonwealth Games.
The Anna Meares Bike Path adjacent to Sir Donald Bradman Drive near Adelaide Airport was named after Meares in 2012. On 9 December 2016, Meares received the Key to the City of Rockhampton.
Meares has a velodrome in Brisbane named after her. It is called the Anna Meares Velodrome and it was opened on 12th November 2016. It is an official venue for the track cycling at the 2018 Commonwealth Games.
Meares is a worldwide ambassador for the Port Adelaide Football Club.
Anna Meares is currently sponsored by Uvex safety and Toshiba