On an article on the club's official website, Palace confirmed that they had bolstered their defence with the signing of the 26-year-old Jamaican international and former Watford man.
Mariappa said: "I'm delighted to be joining Palace and playing in the Premier League again. It's something everyone dreams of doing.
"Playing there last season was a great challenge as it is is the biggest league in the world and you're playing against the best players, so when this opportunity came to me I jumped at it."
The deal becomes one of several Palace are rumoured to be making on the last day, with Ian Holloway making every effort to boost his squad, who recently won their first Premier League game at the weekend.