Brown, 25, originally signed on with the Panthers as an undrafted free agent out of Ohio State back in May of 2014. Carolina declined to tender Brown an offer as a restricted free agent this offseason.
The Bills signed Brown to a one-year deal back in March but was waived coming out of the preseason.
In 2016, Browns appeared in all 16 games for the Panthers and recorded 27 receptions for 276 yards receiving 10.2 (YPC) and scored one touchdown.
King, 27, is a former fifth-round pick of the Broncos back in 2013. He lasted less than a year in Denver before he was claimed off of waivers by the Panthers.
After brief stints with the Jaguars and Buccaneers, the Giants signed him to their practice squad during the 2015 season before cutting him loose earlier in the week.
In 2016, King appeared in seven games for the Giants and caught two passes for 50 yards receiving and no touchdowns.