Katy Bourne was accused of making a false statement about her expenses while serving as the PCC.
The Independent Police Complaints Commission (IPCC) said it was "unlikely" to have affected the Sussex PCC election.
The Crown Prosecution Service (CPS) said there was no case to answer.
Ms Bourne has been cleared of wrongdoing following an investigation into a Facebook post made during the campaign for the 2016 election.
In a report released earlier, the IPCC said: "It is the investigator's opinion that there is evidence to suggest Mrs Bourne posted her comment to social media in order to influence the outcome of the election on 5 May 2016.
"It is highly unlikely that her Facebook comment regarding expenses would have been seen by an audience sufficiently large and had to have made sufficient impact on the voters."
The complaint was then referred to the CPS to see if a criminal offence had been committed. It decided not to prosecute Ms Bourne.
Ms Bourne said: "I was always confident that the facts would speak for themselves and I am pleased the Crown Prosecution Service has determined there is no case to answer."
The Sussex Police and Crime Commissioner (PCC) will not be prosecuted over a complaint she misled the public during the 2016 election.