Brookes, who will take up the new role on 9 March, succeeds Debbie Scott, who moves to a new ambassadorial role at the charity. She has worked for the charity since 1984 and became chief executive in 2005.
Scott’s new role is described in a statement from the charity as "a new outward-facing role working with the charity’s funders, patrons and ambassadors". A spokesman for the charity confirmed that she will be remunerated for this.
A spokesman for the charity would not give details of the salary Brookes will receive. Brookes left his previous job at the Paul Hamlyn Foundation last June after just over a year in post, by "mutual agreement".
Before this he worked for the investment firm Fulcrum Asset Management between 2011 and 2013, having previously been at NPC for 10 years – the first seven as director of research, the last three as chief executive.
He has also worked as a researcher for Amnesty International and as an economist for both Goldman Sachs and the Bank of England.
He was also the co-founder and remains a trustee of the charity Pro Bono Economics, which matches volunteer economists with charities, and was a founding trustee of the charity Social Impact Analysts Associations.
Kate Bolsover, chair of Tomorrow’s People, said that Brookes had already worked alongside the charity in his roles at the NPC and with PBE.
She said: "The success of Tomorrow’s People is built on our relentless focus on clients, and that will continue under Martin’s leadership as it has under Debbie’s. Martin is passionate about helping the long-term unemployed and has a wealth of experience across both the private and voluntary sectors."
Tomorrow’s People had an income of slightly more than £9m and spent £7.8m in the year to 31 March 2014, its accounts show. Having stood at £9.4m and £9.6m for the years 2009/10 and 2010/11 respectively, its income recovered after dipping to £6.8m in 2011/12 and £7m in 2012/13. It has 175 staff, and is based in Eastbourne, East Sussex.