Lockwood, 38, notched-up 397 professional appearances, predominantly with Yeovil Town and Doncaster Rovers, before moving into coaching in 2016 with National League North side Guiseley.
Lockwood said: “I’m delighted to be part of the club and it’s an exciting time to be building foundations for the club to grow into something we as a city can be proud of and call our own.
"There is a tremendous amount of work to be done and it’s exciting to think of the potential to unite the city and surrounding areas of all age groups.
“We will be looking to create an environment where players have the opportunity to grow and enjoy being part of what should be an interesting journey the club has in front of it.
"The opportunity to become part of my home city club is great for me. The team and I will be doing our upmost to create a platform for local talent to progress and showcase themselves and form a relationship with everyone that has a connection to the club and throughout the community to achieve our goals as one.”
Former manager Chris Turner remains at the club to take on the Director of Football role.
He said: "It gives me great pleasure in welcoming Adam to the club.
“We are delighted he has agreed to take on the position of manager with us and we wish him every success.”