The third-rounder the Bills sent to the Panthers is an original Buffalo pick, while the seventh-rounder was acquired from the Los Angeles Chargers last July in exchange for quarterback Cardale Jones.
Benjamin had been having a decent season for the Panthers prior to the trade, and had been one of Cam Newton's favorite targets.
ESPN first reported the move, which came moments before the 4 p.m. ET trade deadline.
Benjamin, 26, brings a welcome size element and physical presence to Buffalo's receiving corps at 6-5 and 245 pounds. He has 168 career receptions for 2,424 yards and 18 touchdowns.
The Panthers had picked up the fifth-year option on Benjamin, making his cap hit next year $8.459 million next season if the Bills choose to keep him.
He was solid last season, finishing the year with 63 catches for 941 yards, and he was on a similar pace this season.
Benjamin has 32 catches for 475 yards and two touchdowns this season.
Without Benjamin and tight end Greg Olsen not expected back from a surgically repaired foot for another month, Cam Newton is left without two risky weapons in his receiving corps.
This trade is hard to process because there are still great unknowns-the greatest of which is the health of Kelvin Benjamin's left knee.
Despite all this, it is worth mentioning that Newton did enjoy his MVP season in 2015 with Benjamin sidelined for the year.
Suffice it to say, Twitter had some interesting things to say about this trade.