Midfielder Newton and defender Dummett are both highly regarded at St James' Park and, with their contracts due to expire this summer, the club have moved to secure their futures.
The pair enjoyed successful loan spells at SPL outfit St Mirren last season and helped the club to secure the League Cup, which was the club's first success in 26 years.
Dummett made 33 appearances for St Mirren after arriving on loan last summer, while Newton featured in 17 games following his arrival in the January transfer window.
Newcastle have now secured the duo on one-year extensions and they are planning to loan the pair out to Championship clubs so that they can continue their development.
A host of Championship clubs are believed to have already registered their interest in signing both players on loan for next season.
The likes of Birmingham, Bolton, Huddersfield Town and Doncaster are all keeping tabs on the duo.