The 40-year-old actress and 31-year-old Marvel star attended the Toronto International Film Festival premiere of their movie, Sing, which screened as a special presentation.
Witherspoon and Johansson, who voice Rosita and Ash, both turned heads in minidresses. Witherspoon wore an off-shoulder number with floral embroidery, while Johansson chose a bright red frock with sheer sleeves and an oversized bow.