Kelly, 26, began her career at Newcastle's North East rivals Sunderland Women and has also played for Middlesbrough Women.
The midfielder played in Iceland for IB Vestmannaeyjar in 2019 and returned to Sunderland in 2021, following a two-year stay at Birmingham City Women.
Kelly has represented England at both under-17 and under-19 levels, boasting vast experience in the Women's Super League from her stints with Sunderland and Birmingham.
More recently, the Middlesbrough-born midfielder has plied her trade in the Barclays Women’s Championship for the Black Cats and has opted to join Newcastle for their upcoming season in the FA Women's National League Northern Premier Division.
Upon signing Kelly, Newcastle Women manager Becky Langley said: "I am very excited to work with Emma this season.
"I've known Emma for a lot of years and she's a talented player. She will bring great leadership qualities from her experience in the WSL and Championship.
"Emma also played full-time in Iceland which brings great experience."
See Emma Kelly in action when Newcastle United Women play West Bromwich Albion Women at St. James' Park on Saturday, 5th August as part of the two-day Sela Cup, presented by VisitMalta. Buy tickets here.