Myler, who was a media adviser on Ed Milibrand’s leadership campaign before joining Burson-Marsteller in 2010, becomes director of communications for Burnham's campaign. Lehal has been made campaign director, working alongside campaign chair Michael Dugher.
The roles will last until the new Labour leader is announced on 12 September and both are on sabatticals from their employers until that time.
Before working on Ed Miliband’s successful leadership campaign, Myler was a special adviser to Burnham during his time as health secretary in the Labour Government, and was also a special adviser to former Home Secretary Jacqui Smith.
Lehal began his career working in Westminster as a parliamentary researcher and was a prospective parliamentary candidate for Labour in the 1997 election.
Burnham is widely seen as among the front runners to replace Miliband as Labour’s next permanent leader. Other contenders who have announced their intention to run are Yvette Cooper, Liz Kendall, Mary Creagh and Jeremy Corbyn.
Myler and Lehal both declined to comment.