Former Pompey boss and Chelsea assistant manager Rix takes on the role following former Boro assistant manager Scott Green's departure earlier this summer.
Ex-Arsenal and England midfielder Rix, 63, has been coaching with Gosport throughout pre-season after being asked to come on board by Gale.
He has now landed a first-team coach position at the club for the forthcoming Southern League Premier South season, working alongside Boro assistant manager Ben Kneller.
Rix, who has been out of the game since leaving his role as AFC Portchester boss in August 2017, says he was immediately interested in taking up a coaching position at the club after being approached by Gale.
And the former Pompey boss insists there's 'huge potential' in the Boro squad he'll be overseeing along with Gale and assistant boss Kneller this season.
Rix said: ‘When Shaun asked me I was interested. I’ve known him for quite a while, I know Iain McInnes (chairman) and Craig Stainton (secretary) as well, so I already had a number of relations within the club.
‘It just appealed straight away, there’s huge potential at the club and there is no doubt about that.
‘I’ve loved working with the lads and have really enjoyed my time so far. Obviously we’ve not spent as long as we liked with them but that’s the level we are at.
‘They’re a great set of lads and have a fantastic attitude. They want to get better and want to learn. I just want to do well as a group because they deserve it.’
Gale has been eager to bolster his coaching staff since former assistant manager Green's summer exit.
The Boro boss believes Rix brings the 'quality' he has been looking for and says it was a 'no-brainer' to add the one-time Pompey boss to his Privett Park backroom team.
Gale said: ‘Scott left us and I was eager to replace him, but also wanted to bring quality in. You
look for lots of things in people and Graham ticked all those boxes.
‘I’ve known Graham for a long time, he has coached and managed at the highest level and he knows the leagues well.
‘I asked him to come and have a look at it and he has really enjoyed his time here. He has brought into what we’re trying to do at the club and I’m glad to get him on board as first-team coach.
‘I’ve got Ben Kneller in as my assistant manager, he does lots of things behind the scenes which people don’t see.
‘The lads have taken to Graham and have really enjoyed working under him, so in the end it was a no-brainer.’
After a glittering playing career which saw him feature more than 300 times for Arsenal and play for England, Rix worked as assistant manager to both Ruud Gullit and Gianluca Villa at Premier League Chelsea in the late 1990s.
He even had a brief spell as caretaker boss at Stamford Bridge in 2000 after the Italian's sacking before going onto manage Pompey and Oxford United.