"Lock U Down" is a song by American recording artist Mýa Harrison on her fourth studio album Liberation (2007). It was written by Harrison along with Jason Boyd, Dwayne Carter, and Scott Storch, with production handled by the latter, and featured Young Money rapper Lil Wayne. The song was released as the album's official leading single after "Ayo!" failed to find success on the charts or at radio and eventually deemed as a promotional single only. The lyrics of the R&B-collaboration speak of a woman locking her man down when she has found the right one.
When released "Lock U Down" received "mixed" to "average" reviews from music critics. Sentinel's editor Brandon Brooks gave Lock U Down a positive review. Brooks called Lock U Down a sure fire hit; complimenting on Harrison's vocal performance commenting, "she has grown up over the years and sound rejuvenated than ever before".The Guardian's Rosie Swash dismissed Lock U Down as a "basic but generally likeable song."
On April 24, 2007, a day prior to the video's official release, Universal Motown uploaded a 27-minute video teaser. The Benny Boom-directed music video for the track was premiered on 106 & Park on April 25, 2007. The heavy dance-laid video includes Mýa dancing in a seemingly abandoned warehouse. Mýa performs a dance routine with a few back-up dancers during the video. Lil Wayne stands next to Mýa when rapping his verses, and Mýa is sometimes seen mouthing the words to his rap. Towards the end of the video, Mýa is seen partying with a couple of friends.