The fans' favourite has already completed three years at Crawley and his best season came in 2015-16 when he scored nine goals in 39 appearances.
His last campaign was ruined by injury to both Achilles tendons and a longer than expected time recovering from a knee operation at the end of the previous season; he made just 15 appearances and scored one goal.
Harrold, 32, is loved by the fans has played in a variety of roles, including goalkeeper and caretaker manager since being signed by John Gregory in June 2014, having played against Reds for Bristol Rovers in the FA Cup.
Three weeks ago Harrold told the Crawley Observer: “I haven’t signed yet but I’d love to stay at Crawley; I think everyone can see whenever I put on a Crawley shirt it matters to me and I always give 100 per cent.
“I’ve played in goal, been temporary manager, fans will have seen I always give my all.”
He said: “At first I had my doubters but then I proved myself with a good season. Last season was frustrating, the most frustrating of my life."