The wing of the business has offices in Jersey, Guernsey and the Isle of Man.
Organic net new business was also up 0.5% in the latest quarter, accompanied by a strong investment performance, the firm said.
Meanwhile, group net flows were up 55% compared to the prior quarter.
“This has been a strong half year for Brooks Macdonald International, reflective of the momentum we see across the Group,” CEO Richard Hughes commented.
“It is pleasing to see a return to positive net flows for us as well as a rise in our [funds under management] to reach a new record level, in a period which was made particularly significant by the launch of our new Isle of Man office as part of our future growth strategy.”