Tointon is 5ft 5in tall. She was born in Basildon in Essex but shortly afterwards moved to Southend. Her younger sister Hannah is also an actress who portrays Katy Fox in Hollyoaks
Tointon began her acting career at age seven. She had speech and drama lessons at school. She also took part in LAMDA examinations, entering local musical festivals performing poetry recitals.
In April 2006 she featured as number 27 in the list of 100 sexiest women in the world, voted for the by the readers of FHM magazine and featured as number 86 on the 2007 list. In September 2006 she was voted sexiest female at the Inside Soap Awards. In May 2007, she was nominated for Sexiest Female at the British Soap Awards. Kara is also nominated for best actress at the National Television Awards on 31st October 2007.