The bank claimed to be the first U.K. retail bank to make use of the voice-activated personal assistant with its mobile banking app on Monday.
Without having to open the app, customers will now be able to make payments by saying: "Hey Siri, pay [Sarah] £15 ($19) with Barclays".
"Barclays has a long history of introducing innovative new products and services to give our customers choice in how they bank," Raheel Ahmed, head of customer experience and channels at Barclays, said in a press statement Monday.
Ahmed added: "The introduction of Siri payments to mobile banking customers is another step forward, giving flexibility and greater choice for all our customers."
Its new feature is only available to customers with an iOS device enabled with touch ID and using Apple operating systems from iOS 10 onwards.
Barclays has previously introduced voice authentication technology for its customers to identify themselves on phone calls, removing the need for passwords.
HSBC also launched its own voice recognition security system last year.
Meanwhile TSB in July became the first European bank to use iris recognition technology for customers using a Samsung Galaxy S8 and future generation smartphones.