Fan favourite Elphick arrived at Pilot Field from Sussex rivals Burgess Hill Town in March 2019 and immediately came part of a miserly U's defence.
During the 2019-20 campaign he was part of a Hastings side which conceded just 21 goals in 28 games - by far the best record in the Isthmian South East - before the season was cut short by the coronavirus pandemic with Hastings three points clear at the top.
The following campaign saw the U's concede just three goals in seven league games - the best defensive record in the division - as Hastings reached the summit of the Isthmian South East.
But the U's season and push for promotion was, once again, curtailed by Covid.
Speaking to the club's official website, Elphick said: “I am delighted to have committed to another season at the ‘U’s.
"I’m enjoying my football at Hastings too much to stop and whilst my body still feels good, I wish to carry on playing.
"Somehow my mission of promotion still hasn’t been achieved so I am highly motivated in helping the club, staff, players and fans in achieving this.
"Hopefully at no fault of our own it’ll be third time lucky!”
U's boss Chris Agutter, also speaking to the club's website, added: "Gaz is in the same bracket as Sammy Adams, all the time he is fit and wants to play he will always be in the team, they are the type of characters who pick themselves.
"Gaz is the most important signing that I’ve made at the club and to have him by my side for next season is massive for me personally and the team as a whole, an indispensable player.
"Lastly and most importantly during our time together he has become a close friend for life and this is what it’s all about.”
And Hastings United CEO Billy Wood said: “Gary is such an important character, I feel like I say that a lot about individuals at Hastings United, which is a credit to the squad in general.
"Gary brings with him experience, know-how and his presence has helped us build an aura, making the ‘U’s a scalp.
"I have a lot of time for Gary and you can see just how much the supporters love him being here too, let’s hope for more wins and Gaz’s bowling ball antics at the end of games in the 2021-22 season!”