Billy and Chris Blanchard-Cooper both swept the board in the Brookfield ward elections for the Liberal Democrats, getting 1,401 and 1,376 votes respectively.
Their milestone was part of a historic day for the Arun district, which saw the Conservatives lose their majority for the first time in the council's history.
Billy, the current mayor of Littlehampton, felt proud to be one half of Arun District Council's first gay couple. The pair got married at Butlins in 2012.The 36-year-old said: "Looking around the room today, there were quite a number of gay councillors, which I think is brilliant. It shows progress, not just here but all across the country. Fifteen years ago, it would not have been so easy.
"The other landmark is that there are at least three disabled councillors elected for the district. I think that is incredible.
"It shows that no matter what someone's circumstances are, if they are passionate, they can do it."
Chris, who is an amputee and uses a mobility scooter and wheelchair, is one of those councillors.
The 44-year-old, who worked for Arun for 10 years, said being disabled 'opened your eyes to a different world' and his victory was a step towards 'equality for all'.
He said: "There is going to be real diversity across the council. It is going to be so different with so many unique viewpoints, whether that is based on disability or sexuality, all sorts."
The couple are both well-known in the town; Billy has been Littlehampton mayor for a landmark two years running and Chris is the former chairman and president of the Littlehampton Musical Comedy Society. Both have been councillors on Littlehampton Town Council.
Billy said: "We want to work with everyone to get as much achieved as possible. There is too much crime in the area, and too many problems in the town centre at the moment.
"Local people know we do listen, and they needed change. They felt let down by the council, and between myself and Chris we will be working hard to be a voice for the people of Littlehampton."
Billy took the seat of former Arun District Council chairman Alan Gammon. As mayor, Billy attended many of the same events as Alan, both in their ceremonial capacities.
He paid tribute to Alan's hard work. Billy said: "I would like to wish Alan well. He has done a very good job and represented the area very well. He is a good guy."
To celebrate, Billy said they would be 'going home, putting their feet up and having a curry'.