The increase came after previously rejected candidates presented new evidence of their credentials, allowing a partial reversal of the mass disqualification of thousands last month.
Those seeking to become one of Iran's 290 lawmakers must first be screened by the Guardian Council, a conservative-dominated committee of clerics and jurists.
The vetting procedure is contentious because the February 26 poll is an opportunity for reformists and moderate politicians to make gains against a currently conservative majority in parliament.
But 6,180 are now eligible, said interior ministry spokesman Hossein Ali Amiri on Saturday, according to official IRNA news agency.
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"In no other elections have we had so many approved candidates, which is partly due to the increased number of registrations," he said.
Among those excluded last month were thousands from Iran's reformist movement, a group with little parliamentary representation.
On hearing of the rejections, reformists asked President Hassan Rouhani, a moderate cleric with close ties to the reform movement, to intervene and seek changes.
Rouhani is hoping his allies can capitalise in the elections after last month's implementation of Iran's nuclear deal with world powers lifted longstanding sanctions.
Reformists have yet to announce how many of their candidates were re-approved. One official said last month that only one percent of its applicants -- 30 from 3,000 -- were deemed eligible but others have said many more would be allowed to stand.
The 6,180 number could rise again, as a number of initially approved candidates were subsequently rejected by the Guardian Council. They have three days to appeal.
"The Guardian Council's opinion is absolute and final except for these 147."
A final list of candidates is to be published on February 16.