Robber Jason Crossland was caught by an off duty policeman after his victim chased after him and shouted for help.
The officer responded to the cries of Mrs Hiral Desai who was making her way home from work in the Intu Shopping Centre in Watford when her handbag was snatched.
Prosecutor Elizabeth Scriven told St Albans Crown Court that when Crossland, 31, from Enfield, tried to pull the bag from Mrs Desai she at first resisted, but when she saw he was much bigger than her she decided to let it go.
Crossland pleaded guilty to robbery on December 1, 2013. He had 14 previous convictions for 26 offences.
Judge Marie Catterson said the robbery was aggravated by the fact it was at night and committed against a lone female, who was vulnerable.
She passed a 10 month jail sentence suspended for 18 months. Crossland will be supervised by a probation officer for 12 months, must attend a Thinking Skills' Programme and carry out 200 hours' unpaid work.
The judge also banned him from entering the Borough of Watford for the next 12 months.