The Newcastle-born goalkeeper has rejoined his boyhood club as a free agent after leaving Motherwell this summer.
Gillespie left the club aged 16 and joined Carlisle United after coming up through the ranks at United’s Academy.
The 28-year-old – who joined Motherwell two years ago after a season at Walsall – has reportedly agreed a three-year deal at St James’s Park, and will replace Rob Elliot, who has been released after nine years at the club.
Speaking after last night’s 2-0 FA Cup defeat to Manchester City at St James’s Park, head coach Steve Bruce said: “I think it’s been signed in the last 24 hours. We’re delighted to have him on board. He was here as a youngster, went away and played some games, and we welcome him back.”