Williamson succeeds David Dickson, who had been elevated from reserve team manager after Ben Clark was sacked at the end of last season as part of a cost-cutting exercise by former owner Dr Ranjan Varghese.
Dickson departed the club by mutual consent on Monday and new Heed owners Neil Pinkerton and Trevor Clark moved swiftly to appoint Williamson - who joined the club last season as a player, before becoming player-coach - into the No 1 role.
He told the club’s official website: "I'm very excited to be the new manager of Gateshead.
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"Last season was thoroughly enjoyable, I really loved it and got a good taste of the coaching side of things and it's something I have always wanted to do.
"I still get to be involved on the pitch as well so it will be fantastic for my personal development but also for the lads that we can bring in and create the same sort of environment that we did last season.
"I still feel that I've got a lot to give as a player and feel as fit as ever. I found that I could have a really good influence on the team coaching from within as well as on the sidelines.
"I'm just going to keep pushing and giving everything that I've got as I have done throughout my career.
"I aim to be a manager that improves people and creates a highly competitive environment but I want the players who come here to know that I will do everything I can to improve them and people and players.
Williamson will be assisted by Ian Watson as he leads the club into their first National League North campaign for 12 years.
Williamson faces a busy summer as Gateshead only have one contracted player in Scott Barrow - and the Welsh wing-back’s deal expires in two weeks.
Williamson added: "At the minute it's very early doors but the aim is to get the club back into the National League as soon as possible."