Harrison, 21, spent his youth career with Blackpool and made three appearances in the FA Youth Cup for the League One side's Academy side before linking up with Hebburn Town in 2022.
The exciting wide player then joined West Auckland, initially on loan, before making that move permanent ahead of scoring 23 goals in the Northern League from left wing.
On signing for the club, Harrison said: "I'm really excited to be joining Whitby Town. It's a great club.
"As soon as I spoke to Lidds, my mind was made up. His plans for next season and the way he wants to push the team forward made it an easy decision for me.
"I can't wait to get started and contribute to the team."
Whitby Town manager Gary Liddle said: "James has been on our radar for some time and was someone I was eager to bring in as quickly as I could post-season.
"He's quick, direct and his 23 goals last season proves he has an obvious keen eye for goal.
"He's excited to take on the challenge of the Northern Premier League and I'm excited to work with him."
For the 2025/26 season, James Harrison is sponsored by Paul Golland.
Photo credit: Tyler’s Mission