The 24-year-old, who can also play at right-back, is set to become the Mariners’ first addition of the summer.
Thurston has spent the last two years playing in the Southern Hemisphere, most recently for Canterbury United in New Zealand’s top flight.
He spent eight years in Manchester United’s academy before spells with Preston North End, Hyde United and FC United of Manchester.
Thurston – originally from the North West – came to the attention of Shields joint managers Lee Picton and Graham Fenton after his return to the country this summer.
He has now put pen to paper and is excited about the future at Mariners Park.
He said: “I’m buzzing to be here.
“It took a little while to get it over the line but now it’s done, I’m delighted and can’t wait to get going.
“The club has big ambitions and I’m excited to be a part of it.”
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