It's not clear yet if Williams will join the practice squad or the active roster. The Saints have not announced the transaction, which won't become official until Friday.
Williams, 25, got NFL looks with the Miami Dolphins and Cleveland Browns as an undrafted free agent out of New Mexico State in 2009. But it was in the CFL where he made his mark, scoring a team-record 17 touchdowns last year (11 receiving, five on punt returns and one on a missed field goal return) with the Hamilton Tiger-Cats. The six return touchdowns set a CFL record.