The New York-born star peppers the phrase throughout her Grammy-winning debut album, Invasion of Privacy.
Last year, she described it as sounding like a "cold pigeon in New York City".
The application was made by her company, Washpoppin, and would cover merchandise like t-shirts and hoodies.
A second application was made for "paper goods, namely cups and posters".
According to Cardi, the phrase is "almost like, 'OK' but the 'okayyyy' is played out" with an extended series of rolled Rs.
It can be used as a simple affirmation or, with a change of inflection, as a comeback to someone who's in desperate need of criticism.
Cardi's trademark application helpfully clarified that "Okurrr" is correctly spelled with three Rs.
But she also made sure to submit an alternative spelling, using two Rs, to combat knock-off merchandise.