One Savings Bank saw its net loans and advances grow by £368m to £7.7bn during the first quarter of 2018.
This compares to net loan growth of £283m for the first three months of 2017.
In a trading update, One Savings Bank also said it had seen organic originations of £689m in the first three months of 2018, compared with £599m for the same period last year.
Andy Golding, the company's chief executive, said: "I am delighted with the performance of the business so far this year.
"Strong levels of applications led to the net loan book growing to £7.7bn in the first quarter with new lending at attractive margins.
"Our lending and retail savings franchises remain strong, and given current levels of applications in our core buy-to-let and commercial businesses, we are confident that we can deliver at least mid-teens net loan book growth this year.
"There is no change to other guidance for 2018."
Earlier this year the challenger bank group, whose brands include Kent Reliance and InterBay Commercial, revealed it had increased its underlying profit before tax by 21 per cent to £167.7m for 2017.
damian.fantato@ft.com
