The 25-year-old has spent the previous three seasons in the National League North with Southport.
He made 90 appearances for the Sandgrounders and scored four goals.
A former Manchester City academy prospect, Oliver has joined Fleetwood Town in 2018 where he made his first professional appearances in a 3-2 defeat to Scunthorpe United.
Prior to his move to Southport, he joined Brentford's B team on loan, going on to make 15 appearances.
Photo credit: Southport
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