Macdonald will become deputy chairman and serve as adviser to the group.
At the same time, the company reported a 7.5% increase in discretionary funds under management (FUM) over the quarter to 30 September, bringing its total FUM to £8.92bn.
During the three months, the group received £170m of net new business, with the majority of the rise being attributed to investment performance, which saw FUM grow by £451m.
Of the results, Macdonald said: “Following on from our annual results announcement last month, we have continued to make good progress in the first quarter of our new financial year, with further organic growth in discretionary funds under management. This has been achieved in spite of a period of weak client sentiment immediately post the EU referendum.
“Notwithstanding potential market volatility, we look forward with confidence as we continue to leverage the growing strength of our brand, investment offering and professional intermediary relationships.”
Connellan brings more than 20 years’ experience in financial services, most recently as head of UK premier and wealth at HSBC.
Prior to HSBC, she has held senior corporate roles including group strategy director at Standard Life and worked as a consultant to the wealth and asset management space as consultant at McKinsey.
She started her career as a fund manager at Newton Investment Management.
The board has indicated that, subject to shareholder approval, Macdonald will eventually become chairman at the group.
Chris Knight, currently chairman at the group, added: “Caroline brings significant wealth management experience that will be critical to delivering the group’s strategy and we are confident that she will bring a valuable external perspective which, together with our experienced management team, will enable us to meet our clients' expectations and to drive further growth in our business.”
Macdonald has been central in the foundation, development and significant growth of Brooks Macdonald over the last 25 years. His new role as deputy chairman will ensure the group continues to benefit from his experience and expertise as it fulfils its growth ambitions.”