His former girlfriend failed to support the prosecution's case by giving "disappointing" evidence.
Sterling was alleged to have attacked 19-year-old model Shana Ann Rose Halliday following a row about a text message, Liverpool Magistrates' Court heard.
But Sterling, from Southport, was formally found not guilty by magistrates when the Crown Prosecution Service withdrew its case after magistrates refused to treat Miss Halliday as a hostile witness.
Sara Drysdale, prosecuting, made an application to the bench asking for the complainant to be "treated as a hostile witness".
She said: "The crown would say that Miss Halliday has demonstrated an unwillingness to tell the truth about what has happened."
She said Miss Halliday, who gave evidence to the court behind a screen, had given "conflicting accounts" to her previous statements to the police and which also differed from her original 999 call to the police on the night in question.
But Stuart Driver QC, defending, said the prosecution was engaging in a "straw-clutching exercise" and just because the witness had given "disappointing evidence" did not mean she was a hostile witness.
He said: "A hostile witness is just that; and it requires a lot more than a witness who disappoints the prosecution by saying things happened in a way that doesn't amount to a criminal offence. That's just what we have here."
At times Miss Halliday failed to answer prosecution questions and was often so quiet she was inaudible.
She told the court: "We just had a heated argument because I seen a text on his phone and asked who it was. We were pushing and shoving, both of us, and I started it because I was trying to get his phone."
Mr Driver added: "She has given evidence, slowly but in detail, and it's unfavourable to the prosecution case. She is far from being a hostile witness."
Anthony Leo, chairman of the bench, told the court: "Although she is an unfavourable witness for the prosecution, she is not hostile."
After the bench made its decision, Miss Drysdale said there was "no longer a realistic prospect of conviction".
Sterling, wearing a black suit, white shirt and blue tie, was called back into the dock and formally found not guilty to the charges.