The Universal and Illumination Entertainment film will also star Seth MacFarlane, Taron Egerton and Tori Kelly, reported Variety.
McConaughey, 46, will voice a koala, who presides over a once-grand theater that has fallen on hard times.
He decides to regain the glory by producing the world's greatest singing competition.
Contestants are a mouse (MacFarlane), a timid teenage elephant (Kelly) with a case of stage fright, an overtaxed mother (Witherspoon) tending a litter of 25 piglets, a young gangster gorilla (Egerton) and a punk-rock porcupine (Johansson) struggling to shed her arrogant boyfriend.