It was triggered following the death of well-respected veteran councillor David Simmons.
He was said to have ‘helped countless people’ and served Hillside ward from 2014 up until his death.
Leila Williams (Con) was elected as the new Hillside ward councillor on Thursday (December 2) with 414 votes. Voter turnout was 21.9 per cent.
Two other candidates contested the seat: Green Party’s Russell Whiting who received 175 votes and Rebecca Allinson from the Labour Part won 148 votes.
Ms Williams was born in Brighton and lives in Southwick.
She is a mother of two and said: “If you want something done, give it to a busy person.”
Ms Williams has worked for the NHS for 12 years and hopes to bring ‘a wealth of public sector experience’ to Adur District Council.
She was elected on a promise to ‘reduce, regenerate and rewild’ in Southwick.
Speaking after the by-election results were announced, she said: “Pavement parking is a big issue and it affects more than one area.”
She would also look to ‘regenerate Southwick Square’, ‘further roll out the rewilding scheme’ and ‘reduce the speed limit on Old Shoreham Road’.
“Reducing the speed limit on the Old Shoreham Road, I know, has had a mixed reception,” she said.
“Not everyone’s in favour of reducing the speed limit, but there are certainly plenty of people who think, for safety, it would be a really good thing for us to try and push forward with the county council.
“My fellow councillor Angus Dunn and I will certainly be putting that at the top of our list.”
The new Hillside councillor said she would represent the ward with ‘great pride’ and acknowledged that she had some ‘big boots to fill’.
“So many people that I’ve spoken to on the doorsteps have been commending Dave [Simmons] on his excellent service to the council and how he helped people and represented the voice of Hillside very effectively,” Ms Williams said.
“So I’m absolutely aware of that obligation and I do so with great pride.
“Hillside remains with two Conservative district councillors and I look forward to working with the people of Hillside and doing as much as I can to make their voice heard.”
Hillside ward has two representatives on Adur District Council: newly elected Leila Williams, and Angus Dunn (Con).
Ms Williams previously contested the Southwick Green ward at May’s council elections but lost out by 61 votes to Labour’s Robina Baine.