Ms Ellis will be responsible for the development and implementation of the EYFS, including the Communication, Language and Literacy Development (CLLD) programme.
Her current job at National Strategies is leading the Every Child A Talker programme.
Her previous work includes developing the CLLD programme, including the phonics programme Letters and Sounds, and overseeing it in its first year, and she also helped to develop the EYFS.
Ms Ellis, whose work in education spans more than 30 years, started her career as an early years teacher in nursery, primary and special education before she became an Ofsted inspector. She subsequently joined Somerset local authority as an early years adviser and senior adviser for the Foundation Stage.
Ms Ellis has spent much of her working life promoting the importance of early identification of children with specific developmental needs. She sees developing competence in language as being the 'golden thread' to improving life chances.
National Strategies said that Ms Ellis would be an excellent champion for young children and the early years sector.
Ruth Pimentel resigned as national director unexpectedly in November after nearly three years in the job.
She had been involved in developing the Foundation Stage from its launch in 2003.