O'Malley, who made her Broadway debut as an Enchanted Object in Beauty and the Beast, played Celeste #1 in the 2008 revival of Sunday in the Park, Grace Farrell in Annie and the lead role of Betsy in Honeymoon, among other credits.
Here is a clip from her performance as concert mistress Alison Beck in the Jan. 6 TV show, with series star Debra Messing. O'Malley appears at the 0:38 mark.