PC Mary Ellen Bettley-Smith was cleared of assault by a jury at the crown court in the case.
The jury deliberated for three hours and two minutes before acquitting Ms Bettley-Smith, who struck Mr Atkinson three times with a baton after he was tasered to the ground by PC Benjamin Monk.
Bettley-Smith told her trial that if Mr Atkinson had gotten to his feet, she would have been seriously injured.
The woman told the jury that she used her baton as a last resort as she desperately tried to control the man, who she said was resisting and trying to get up.
The trial judge thanked the jury after they acquitted him.
In July 2021, Monk was sentenced to eight years in jail after he was found guilty of kicking and tasering Mr. Atkinson.
The retired footballer, who was capped by the England B team and played for two other teams, was looking forward to private health treatment due to start on the day he was killed, was told at the re- trial.
Shortly after being tasered, he lost consciousness and died in the hospital.
Bettley- Smith and Monk, who were in a relationship at the time, were sent to the scene to restrain Mr Atkinson after his mental state became disturbed.
Bettley-Smith lost her cool and "pummelled" Mr Atkinson with a baton, which they accepted did not contribute to his death.
Bettley- Smith told the court that she used the baton because she thought the ex- footballer still posed a threat after he was tasered for a third time.
The officer, who is 5ft 5ins tall, said the incident was the only time she had used her baton during her full-time service.
The man did not flinch or feel pain when he smashed a window after being tasered twice.
She said she thought he was going to fight. He tried to get up on his hands and knees.
I was afraid that Mr. Atkinson would get up. I was afraid that if he got up, I would be in serious danger.
I would not have used my baton that night if I had the chance. I didn't lose my cool or get angry.
Bettley-Smith, a social work graduate, said that being told of Mr Atkinson's death had left her feeling overwhelmed and that the feelings had not gotten any easier.
She said she lived it every day.