The 26-year-old forward, who was born in Brighton, came through the Seagulls academy and made two appearances in the Championship under Sami Hyypia in the 2014/15 season against Sheffield Wednesday at the Amex in September 2014, before then coming off the bench at St.Andrew’s against Birmingham.
During his time at Albion, Fenelon went on loan to Torquay, Rochdale, Tranmere and Dagenham & Redbridge.
He then left the club in July 2015 to join Crawley on a free transfer.
He only spent one season at The People’s Pension Stadium before then signing for National League side Aldershot on a free transfer.
Fenelon joins Horsham from National League South side Billericay where he played last season.
But after their campaign was curtailed in February, Fenelon knew he wanted to play more locally.
He said: “When our season ended in February, I knew that this season I wanted to play more local, and Horsham was my first choice.
“In the back of my mind I knew that if we could work something out, this would be the place for me.
“I live locally, I knew a few of the boys and my brother used to play here so I used to come and watch at the old ground.
“It’s a place that I know so I already feel at home, and when I met with Dom, I knew this was the right fit for me.”
There will be a couple of familiar face to Fenelon in Charlie Harris, Doug Tuck and Harvey Sparks, who he played with during his time at Albion’s academy.
Horsham boss Dom Di Paola was delighted to have signed Fenelon.
He said: “He’s a bolt out of the blue, but one we can’t turn down.
“He’s quite an athletic forward and can play anywhere across the front line, and he;s got really good pedigree.
“He knows quite a few of the boys from his time at Brighton so he should fit in really well.”