Cox, 46, and Van Holt, 43, have reportedly been dating for at least 10 months, but have only gone public after Cox's divorce with David Arquette was finalized last month.
Cox and Arquette announced in October 2010 they were ending their 11-year marriage, and legally separated in December 2011. After they went public with their split, Arquette said he thought Cox was having an "emotional affair" with her costar.
"Cougar Town" will have at least one more season -- its fifth -- on TBS.
Notable deaths of 2014 [PHOTOS]