Councillor Kieran McCarthy, 55, will make the announcement at a meeting of supporters in his hometown of Cobh that he will run as a candidate in the Cork East constituency.
It is expected he will take votes away from the sitting Sinn Fein TD Sandra McLellan, who Mr McCarthy and other Sinn Féin members have criticised in the past.
Mr McCarthy, a married father of five, was expelled on June 22 after being a Sinn Féin member since 1981.
Last week, the party issued a statement saying it was reinstating him until a full inquiry into the finances of the Cobh cumann had been completed.
Mr McCarthy said he did not believe the reinstatement offer was genuine and rejected it. “I am taking a case [against Sinn Féin] to the courts in relation to this and I would prefer not to comment any further on it until that has been resolved,” he said.
He was first elected to the former town council 21 years ago and was elected to the county council last June with 2,500 first preferences.
“The old faithful [Republicans] are very angry about what happened to me,” he claimed. “Other people have also come up to me and said they would never have voted for me before because of the party I represented. They say they will now do so because they recognise the work I have done and because I will be running as an Independent candidate.”