The movie will centre on "power and the price that is paid for power" and be directed by Phyllida Lloyd (Mamma Mia!) from a script by Abi Morgan (Sex Traffic).
"The prospect of exploring the swathe cut through history by this remarkable woman is a daunting and exciting challenge," said Streep. "I am trying to approach the role with as much zeal, fervour and attention to detail as the real Lady Thatcher possesses - I can only hope my stamina will begin to approach her own!"
Jim Broadbent will star as the former Prime Minister's husband Denis Thatcher, while Alexandra Roach and Harry Lloyd will portray the Thatchers in their younger years.
Olivia Colman, Nicholas Farrell, Susan Brown, Roger Allam, Anthony Head, Julian Wadham, Pip Torrens, Nick Dunning, Richard E. Grant, David Westhead, Angus Wright and John Sessions are among the supporting cast for the biopic.
The Iron Lady began production in the UK on January 31.