Pamela Wallin's five colleagues from Saskatchewan were split on whether to suspend her for two years without pay.
The full senate voted 52-27 to do exactly that, with 12 abstentions.
Three of six Saskatchewan senators voted with the majority: Raynell Andreychuk, Denise Batters and David Tkachuk.
Two Saskatchewan senators in the Liberal caucus, Pana Merchant and Lillian Dyck, voted against the motion to suspend.
Wallin herself abstained from the vote, and later said it was "an extremely dark day for democracy."
The Senate also voted to suspend senators Patrick Brazeau and Mike Duffy. The three have come under official scrutiny over their spending.
Wallin, a former member of the Conservative caucus who became an independent earlier this year, was suspended for allegedly claiming improper expenses.