The District Court judge faces up to five years in prison for attempting to deceive an elderly friend and client out of half of his €1m estate.
Her pension will be a mere €106 a week compared to the €2,845 she earned a week from her judicial appointment because she served only three years in office.
The former solicitor, who ran a practice in north Dublin, Perrin was appointed as a District Court judge in 2009, just a month after tricking octogenarian Thomas Davis into leaving a huge sum of money to her two children.
She maintained her innocence throughout her seven-day trial at Dublin's Circuit Criminal Court but was found guilty.
Perrin of Lambay Court in Malahide had pleaded not guilty to deceptively inducing Mr Davis to bequeath half of his estate to Sybil and Adam Perrin at Heather Perrin's office on Fairview Strand on January 22, 2009.
The former director of the Girls Brigade International Council, the Christian organisation for young girls, resigned with immediate effect last night sparing the Government the prospect of impeachment proceedings.
Perrin has been on long-term sick leave from the bench and has remained close to her Malahide home since being sentenced.
The 60-year-old, who earned €147,961 a year as a District Court judge, is entitled to a modest pension of 3/80th of her salary for her three year's service. It will be paid to her on reaching pensionable age.
Last week she was found guilty by a unanimous jury of deceiving Mr Davis, whose wife Ada the judge knew through the Irish Girls Brigade.
Her defence team suggested that Mr Davis suffered memory problems and had somehow "forgotten" leaving half of his estate to the Perrin children.
In just under four hours the jury decided that Mr Davis, who left €2,000 each in his will for the Perrin children, was not suffering memory loss.
Separate charges of deception relating to the will of Mr Davis's wife Ada, were dropped before Perrin's trial because Mrs Davis's mental state had declined to the point where she was unable to give evidence.
Prosecutor Dominic McGinn said Perrin fought the case using "lies, half-truths and deceptions".
A brief statement from the Courts Service, issued last night, said Judge Heather Perrin had offered her immediate resignation from the District Court.