The move relates to her involvement in a controversial rice subsidy scheme.
Earlier on Friday, the attorney general also announced that Ms Yingluck would face criminal charges over her role in the scheme.
A court removed Ms Yingluck as PM in May 2014, days before the military ousted her government in a coup.
On Friday, 190 out of 219 lawmakers present in the military-backed National Legislative Assembly voted to impeach her.
The votes were written on a whiteboard as they were tallied, and broadcast on national television.
The allegations against Ms Yingluck centre around a rice subsidy scheme in which her government bought rice from Thai farmers at a much higher price than on the global market.
Anti-corruption investigators have accused Ms Yingluck and her party of using the scheme to buy votes from farmers and allowing government associates to profit from it.
Ms Yingluck has maintained that she was not involved in the scheme?s day-to-day operations.
Her supporters say the claims against her are a ruse to remove her from politics.
Ms Yingluck?s party is the most popular in Thailand and has ? under various different names ? won every election since 2001.