The 24-year-old former Bristol City player played the first half of last season at Dover Athletic and the second at former club Torquay.
In total he made sixty-five appearances and scored 6 goals in two spells for the Gulls, playing against Gateshead twice in each of the last two seasons.
"Gateshead have always been an organised team when I've come across them in the past and I'm happy to be moving north," said Ajala. "Last season was a strange one for me and while I could have stayed at Torquay I wanted to move on and enjoy my football again.
"Hopefully I can show what I'm all about and be a regular in the side rather than being an impact player off the bench.
"I've played in the Football League on loan at AFC Wimbledon and had a couple of games off the bench in the Championship for Bristol City.
"The Football League is where I want to be and it would be great if that was at Gateshead. We should certainly have a good season.
"There have been a number of impressive signings and you have to aim high - and that's the title and automatic promotion.
Ajala, the tenth signing of a productive summer, had a six-month spell at Hull City and has also played for Welling United and Hayes & Yeading United.
Manager Neil Aspin believes Ajala is another quality addition to the squad: "He is another that will bring pace to the side. He will give us that in wide areas and has experience and pedigree at this level.
"While he has had a taste of League football and has the attributes to do really well he has still to fulfil his potential - hopefully he'll do that at Gateshead.
"Wingers, by their nature, can blow hot and cold. He had a trial at Newcastle a few years ago and was keen to come to Gateshead."
Ajala has signed a one-year contract at the International Stadium.