The Morning Show actress rocked a sequined one-shoulder little black dress from Saint Laurent, accessorized with matching pointed-toe pumps and Nikos Koulis hoop earrings. For glam, Witherspoon looked gorgeous with her blonde lob styled in effortless waves.
Witherspoon will be presenting onstage at tonight's ceremony, which is dedicated to celebrating the legacy of women in country music.
Other presenters include Hannah Brown, Kristin Chenoweth, Bobby Bones, Blanco Brown, Jennifer Nettles, Martina McBride and more.
Witherspoon's friend and Big Little Lies co-star Nicole Kidman also graced the red carpet with husband Keith Urban.