The film-maker has also agreed to co-host a fund-raising "Dream Dinner" in San Francisco on 19 November (05) alongside fellow supporters CARLOS and DEBORAH SANTANA, VICTOR MACFARLANE and BONNIE FISHER and BORIS DRAMOV.
The memorial will be based in US capital Washington DC, and will cost an estimated $100 million (GBP56 million).
Fellow major contributor SHEILA JOHNSON says, "This generous contribution from George Lucas will help honour the principles for which Dr King stood: justice, hope, and freedom for all. By making this contribution and co-hosting the San Francisco Dream Dinner, Mr Lucas adds to the tremendous momentum and support the MLK National Memorial Foundation has received."
King Jr was assassinated in 1968.