Mrs Downs, who joined OUSA this week, brought to the role an extensive knowledge of the tertiary sector, OUSA president Paul Hunt said.
''The executive are pleased to have someone of Debbie's calibre on board to lead the OUSA staff,'' Mr Hunt said.
''I look forward to working with Debbie to ensure OUSA provides services and support which benefit all 20,000 students at Otago.''
Mrs Downs replaces Darel Hall, who left the role of general manager in December last year to follow his wife to Wellington for work.
The title of general manager was informal and OUSA would now use the official title of chief executive for the role.
Mrs Downs hoped to tighten the bonds between the University of Otago and OUSA.
She began her career with the university and had a passion for general management, in particular human resource management and accounting, she said.
''OUSA does an amazing job, and this role is a perfect fit for me,'' she said.
Acting chief executive Matt Tucker would return to his role of OUSA student support centre manager.
