Three shops called the police while the offender lay writhing under the men pinning him to the ground. They restrained the man for around 10 minutes.
Das said she believed people had handed the woman back her phone and wallet and she had left the scene quickly as "she must have been quite shaken".
"It sounded like he just stole it right out of her hands."
Das was proud of how around 15 people off the street stepped in to help out. She said street harassment was rife in the inner city but it was good to see people would help when someone needed it.
"Half of High St came down to help ... I'm so happy with humanity right now.
"Everyone learnt if you make enough noise someone will hear you."
A police spokeswoman said three calls in a row were received at 5.50pm reporting that a woman had her wallet stolen by a man on High Street in central Auckland.
Police immediately went to the scene and arrested the offender.
The spokeswoman said the people who went to the victim's aid acted "bravely and sensibly".
"While we don't encourage people to put themselves in danger to prevent a crime, in this instance the people who went to the victim's aid acted bravely and sensibly.
"We're grateful for their assistance in preventing this crime."
The 20-year-old man has been charged with theft and will appear in Auckland District Court on April 11.