"I Do" features a hook crooned by SZA. Despite the Top Dawg R&B singer's busy schedule, she made a promise to Cardi that she would find time for a collaboration, which resulted in this song.
Cardi and SZA proclaim during the song that they do just what they like. SZA croons on the hook:
I left a nigga on read 'cause I felt like it Dress me down in that Raf, Saint Laurent jacket Dapper, dapper, I look fine and my checks divine No wonder, wonder why I do whatever I like I do what I like, I do, I do
Cardi B sums up the song's concept in verse two when she raps:
Good girls do what they told Bad bitches do what they want
The beat comes courtesy of Canadian producer Murda Beatz, a frequent collaborator of both Migos ("MotorSport") and Drake ("Nice For What"). He was assisted by his frequent collaborator, the German duo CuBeatz.
The hook of "I Do" was penned by Los-Angeles based songwriter Nija Charles (Jason DeRulo's "Colors"). Nija told Genius that she didn't know the song was going be on Invasion of Privacy until around a fortnight before its release.
Nija drew inspiration from her own life experiences when penning the hook:
"19 years old, getting flown out everywhere, I was with Kodak Black the night before, so I was just in a great mood," she recalled. "When the beat came in, I went into savage mode and the first thing that came out on the mic was, 'I left that nigga on read, cause I felt like it.' I wanted to channel how I feel when I look in the mirror in the morning after getting washed in dressed. The hook just came across as feeling invincible."