According to NFL.com, the Bills are expected to interview Smith soon.
The Bears were 81-63 under Smith in nine seasons, including a 10-6 mark in 2012. But the Bears have made only one playoff appearance since 2007.
There are currently six head coach openings in the league other than the Bears', and ESPN initially reported that four team have already contacted Smith.
General manager Phil Emery cited Smith's inability to consistently get the Bears into the postseason and their long list of offensive struggles over the years as reasons for the coaching change.
The Bears' defenses under Smith consistently ranked among the league's best and have produced plenty of takeaways. The Bills were 22nd in total defense this season and were 26th last year.
The Bills fired coach Chan Gailey on Monday.