The single, which features Pharrell Williams and Nile Rodgers and pre-empts the release of their eagerly anticipated Random Access Memories album, has overtaken previous hit One More Time to be the biggest selling single of their career.
Get Lucky sold 163,000 in the second week of release putting it on target to become one of the biggest selling records of the year.
Elsewhere, British dance act Rudimental are also currently enjoying success in both the singles and album charts.
Previous number one, Waiting All Night featuring vocalist Ella Eyre, sold 81,000 copies to take the number two spot in the charts.
Their debut album, Home, which features the likes of Emeli Sande, John Newman and Angel Haze has hit the top of the charts in its first week of release.
Disclosure, another hotly tipped dance act, have hit the upper echelons of the UK singles chart with You and Me featuring Eliza Doolittle. The release follows the success of White Noise featuring AlunaGeorge by reaching number ten in the charts.