The bank says it will acquire a savings business worth £5.5bn and a mortgage book with outstanding balances of approximately £8.8bn.
It adds that 270 Standard Life employees will transfer to Barclays once the deal is complete.
Frits Seegers, chief executive of Barclays Global Retail and Commercial Banking, says Standard Life “is a good fit” with Barclays existing UK retail banking business.
Standard Life recently named finance director David Nish as its new group chief executive.
His appointment came at the end of 12 months that has seen the insurer make a number of senior marketing appointments and restructure its UK marketing team.
Marketing operations director Simon Esberger joined in October last year, while Andrew Gillespie was named managing director for marketing across the UK financial services business last December.
The appointments came ahead of a restructure that involved the separation of marketing and product development and the creation and abolition of a number of roles.