"Sideline Ho" is a song by American R&B recording artist Monica. It was written by Harvey Mason, Jr., Damon Thomas, Antonio Dixon, Eric Dawkins, Steve Russell, and Durrell "Tank" Babbs for her fourth studio album, The Makings of Me (2006). It was co-produced by The Underdogs and Tank, and released as the album's third single in the first quarter of 2007. The song opened at number 77 on Billboard's Hot R&B/Hip-Hop Songs chart on early airplay alone, and achieved a peak of number 45 on that chart.

Although "Sideline Ho" had a successful debut on the R&B charts, J Records refused to agree on producing a music video for the song at first, and on January 19, 2007, a video clip of Monica asking fans to sign an online petition to help convince her record company to release a video for the single was leaked onto the internet. While several sources reported that the singer and her team "had started writing treatments for the 'Sideline Ho' video" by late February 2007, ideas for a video were eventually scrapped.

"Sideline Ho" is one out of two songs on The Makings of Me Monica worked on with production team The Underdogs and singer-songwriter Tank at Doppler Studios in Atlanta, Georgia. The concept of the song came up while Monica was brainstorming ideas with several musicians and was inspired by an ex who cheated on her with a video model. Speaking of how the song came about, Monica stated in an interview with Billboard in August 2008, that the record was about "me being in a relationship years ago and somebody just disrespected to the fullest." During the process, she told Tank about a situation where an ex of hers "blatantly, openly cheated - as if people didn't know who his girlfriend was! And just the sound of her name would make my flesh crawl. So he was like, 'Well what did you call her?' I said, 'She has no name. She has no importance [...] I always referred to her as the 'sideline ho,' because she was too comfortable with her position." While Monica remarked that she "never would've thought he would come back in the room, like 'that's the title of the song', she went on to "give him play by play details", which she had previously documented in a self-written poem and "that really stood out in my mind and they created a song around it."

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