Singer Janelle Monae performs at the 2018 Global Citizen Festival in Central Park on Saturday, Sept. 29, 2018, in New York. Picture: AP

American singer Janelle Monae has been added to the cast of the Harriet Tubman biopic.

The 32-year-old singer will star alongside the likes of Leslie Odom Jr, Joe Alwyn, Jennifer Nettles, Clarke Peters and Vanessa Bell Calloway in 'Harriet', which will tell the story of the American abolitionist.

The upcoming movie - which is being directed by Kasi Lemmons, who also co-wrote the script with Gregory Allen Howard - follows the activist on her escape from slavery and her subsequent efforts to help dozens more slaves achieve freedom.

'Harriet' - which will be Janelle's latest film since starring in 2016's 'Hidden Figures' and 'Moonlight' - is due to begin filming in Virginia later this month.

Janelle - who recently released her latest album, 'Dirty Computer' - is also set to star in the upcoming animated movie 'UglyDolls', according to Variety.

The animated family adventure is based on the popular toy brand, and Janelle is also expected to perform original songs for the movie.

Meanwhile, Cynthia Erivo - who previously starred in a Broadway revival of 'The Color Purple' - is set to play the titular role in 'Harriet'.

And the British actress has admitted she's desperate to make the most of the opportunity, saying she's been trying to "soak it all in". 

Reflecting on the exciting opportunity, Cynthia previously said: "I'm completely grateful to be able to play that role. I hope I do it justice."