Bill Walker, 71, was found guilty at Edinburgh Sheriff Court last month of 23 charges of assault against his three ex-wives and a former step-daughter from 1967 to 1995.
The Dunfermline MSP has refused to resign his seat despite public pressure and a motion signed by 90 MSPs demanding his immediate departure from the Scottish Parliament.
Members and supporters of Scottish Women's Aid, NUS Scotland Women's Campaign and Zero Tolerance gathered for a rally outside Holyrood as MSPs returned from their summer break.
One of the organisers, NUS Scotland women's officer Stacey Devine, said resigning is the "only decent thing" Walker can do.
She said: "We are here to send a clear-cut message to Bill Walker that he is not fit for office and that he should not have the privilege of representing the people of Fife and the people of Scotland."
Ms Devine also said questions are to be asked about why the case was prosecuted at summary level, which restricts the sheriff's sentencing power.
Walker, of Alloa in Clackmannanshire, is due to be sentenced on September 20.
The former SNP MSP, who was ejected from the party when the allegations surfaced, denied the charges against him, meaning the case went to trial over 10 days.
A proposal for Walker to have his wages curtailed if he is jailed, is being consid-ered by authorities at Holyrood.
A total of 90 MSPs had signed the motion urging Walker to "vacate his seat in the Parliament immediately".