The 26-year-old has joined for an undisclosed fee, believed to be in the region of a club-record amount, and becomes the second addition within the space of an hour following the signing of Tottenham defender Zeki Fryers.
McArthur started his career at Hamilton before moving south of the border to join Wigan - where he established himself in the first team and played in the famous FA Cup final success over Manchester City in 2013.
The Latics were relegated the same season and McArthur remained at the club as they failed to achieve an immediate top-flight return but has now completed a deal to join Palace and took to Twitter to thank Wigan.
Thanks to @LaticsOfficial for an amazing 4 years. They will always have a place in my heart but time for new chapter with crystal palace.
Fryers, 21, became the Eagles' first signing of transfer deadline day after joining from Tottenham on a three-year deal.
Fryers made only two Premier League appearances during his spell at Old Trafford before moving to play in Belgium with Standard Liege.
The England Under-19 international returned to England when he signed for Spurs in 2013 but could not establish himself at White Hart Lane, with Press Association Sport understanding a fee of £3million seeing him move across London to Palace.
Palace then completed their business with a late loan move for Wolves striker Kevin Doyle.
The Republic of Ireland international ended last season on loan at QPR whilst his parent club were gaining promotion back into the Championship.
Doyle, 30, has yet to turn out for Kenny Jackett's side this season but has joined Palace until January to bolster Neil Warnock's attacking options at Selhurst Park.
The new signings were brought in by new Palace manager Neil Warnock, who returned for a second stint managing Palace last week, succeeding Tony Pulis, who quit the club on the eve of the new Premier League season after a row with the board over transfer policy.
The former Sheffield United boss' first act in charge at Selhurst Park was to complete the season-long loan deal for Wilfried Zaha's return from Manchester United.
Zaha fired an injury-time goal at Newcastle on Saturday as Palace stole a 3-3 draw in the north east.
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