The victim was in Halesowen Street, Oldbury at around 8.15pm on Saturday when he was threatened with a machete.
The offenders went on to steal the boys phone, coat and hat.
Police were alerted to the robbery just after 8.30pm by the victim’s dad and quickly deployed officers to the scene.
An 18-year-old man was arrested and a large machete recovered.
Further enquiries found that four other suspects had made off in a taxi.
After identifying the taxi firm, police intercepted it in Dudley Road at around 8.50pm where four passengers – two aged 15, one 16 and a 17-year-old – were arrested.
All five have been arrested on suspicion of robbery and knife possession and remain in custody.
Superintendent Phil Asquith praised the rapid response from officers.
He said: "We sent officers to the scene immediately.
"They’ve quickly identified a suspect and through some enquiries at the scene identified the taxi, tracked its movements and pulled it over.
"We had all five in custody just 20 minutes after receiving the 999 call – so a really good job.
"This must have been a really scary, upsetting incident for the boy. I’m pleased we’ve managed to reunite him with his property and wish him all the best for the future."