Chris Macdonald, who has been an integral part of the wealth management business since its inception, will become deputy chairman with effect from today, subject to regulatory approval.
Connellan's appointment, first announced back in October, comes at a time when the group’s discretionary funds under management (FUM) exceed £9.33bn.
Over the second half of 2016, the wealth manager posted double digit growth across all three of its chief investment divisions and boosted its pre-tax profits by 49% to £8.16m.
Prior to joining Brooks Macdonald, Connellan was head of HSBC’s UK Premier and Wealth division.
She also worked at Standard Life as a group strategy director, having begun her 20-year career as a fund manager at London-based Newton Investment Management.
Noting a period of "significant opportunity and change in the wealth management sector", she said: "I am inheriting a strong legacy and this, combined with the strength of our adviser relationships, positions the group well for the future.
"I look forward to building upon the success to date and, together with our experienced team, ensuring we continue to meet and exceed our clients’ expectations.”
Connellan also said she was prepared to steer the group into its next phase of growth and would be pursuing further opportunities to develop the business.
“My focus will be on enhancing our offering and service levels, developing the efficiency of the business, and continuing to adapt to the fast changing competitive and regulatory landscape."
She added: “I feel passionate about the important role that Brooks Macdonald plays, in partnership with advisers, in helping people plan and save for their future needs.
"As such, I am looking forward to leading a business that has such a strong track record and reputation in the marketplace.”