Although the exact circumstances were unclear last night, it was understood Mrs Redknapp's coat got trapped in the door and her foot was still in the Range Rover's footwell as it pulled away.
She screamed in pain and her husband slammed on the brakes - but not before her foot had been seriously injured.
One local told the Sun: 'I was in a shop and a couple of people came in and said, 'Crikey, there's a lady who's been dragged along the road'.
'Then someone else came in and said it was Harry Redknapp who had just dropped his wife off.
'I heard as he drove off she got her coat caught in the door. She was dragged along the road before he realised.
'I think she has been badly injured.'
Others witnesses said the former boss of Tottenham, West Ham, Bournemouth, Southampton and Portsmouth clubs looked shaken.
A South Western Ambulance Service spokesman said: 'We were called at 11.49am to Poole Road, in Bournemouth.
'There was one female casualty in her 60s. She had a foot injury and has been taken into hospital.'
Mrs Redknapp had recently been in the audience on BBC's Strictly Come Dancing cheering on daughter-in-law Louise.
Mr Redknapp was himself seriously hurt in a road accident near Rome which killed friend Brian Tiler in 1990.
They were in a minibus that was hit by a car during the Italia 90 World Cup. Three young Italians also died.
Mr Tiler was a former AFC Bournemouth managing director. The two men became friends when Harry managed the club.
Mr and Mrs Redknapp have two sons together Jamie, a former England football player and Daily Mail columnist, and Mark, a professional model.
Mr Redknapp's nephew is former England captain Frank Lampard.
In 2006, the BBC's investigative programme Panorama showed Mr Redknapp on camera expressing his interest in approaching a player illegally in order to arrange a transfer.
Following an investigation by HMRC in 2010, he was charged with two counts of cheating the public revenue, but was later found not guilty at a trial.
Last night, representatives for Mr Redknapp denied that an incident had taken place.