Harris, who recently signed a new contract at Vitality Stadium, joins the Spitfires following a memorable 2024/25 season, which saw him named in two Premier League matchday squads.
The Wales under-21 international was on the bench for the Cherries’ against Crystal Palace and Fulham, having impressed first-team head coach Andoni Iraola.
The 20 year old, who has National League South experience, was a key figure as Cherries won the the Professional Development League Southern Group last season.
In joining the Spitfires, Harris is following in the footsteps of his father, Andy, who made 101 appearances for [Eastleigh](http://www.dailyecho.co.uk/news/district/eastleigh/) between 2006 and 2009.
"I’m really excited to be here at Eastleigh and can’t wait to get started," the versatile defender said upon his arrival at the Silverlake Stadium.
"It’s a great opportunity for me to continue developing and to contribute to a team that’s hungry for success.
“I’ve heard a lot of good things about the club and the fans, and I’m looking forward to showing what I can bring on the pitch.”
Harris’s development squad teammate Noa Boutin enjoyed a productive loan spell with Eastleigh last season, featuring 34 times as they finished 13th in the National League.
Eastleigh, who are managed by former Southampton goalkeeper Kelvin Davis, meet the Cherries development squad in a pre-season friendly on Saturday 19th July.
The National League fixtures are due to be announced on Wednesday, July 9 with the season kicking off on Saturday 9th August.
Harris becomes the latest Welshman in the Spitfires squad, joining captain Jake Taylor, defender Lloyd Humphries and summer signing Kieron Evans.
Eastleigh have also signed Antigua and Barbuda international goalkeeper Nick Townsend, and former Maidstone duo Temi Eweka and Aaron Blair.