Jackson's meeting Monday with Blatt was first reported by The Vertical.
ESPN.com reported last week that the Knicks' search was focused on Blatt and Knicks interim head coach Kurt Rambis. Rambis continues to receive strong consideration for the opening.
Blatt guided the Cavaliers to the NBA Finals last season before his abrupt firing in January with the Cavs leading the East at 30-11.
No coach in league history had been dismissed in-season with a higher winning percentage than Blatt's .732.
Blatt is a known quantity to Knicks general manager Steve Mills, who played with Blatt at Princeton.
Jackson also discussed the Knicks' head-coaching vacancy with Golden State Warriors assistant Luke Walton earlier this month, but both sides said it was not a job interview.
Rambis is receiving strong consideration to stay on despite his modest 9-19 record as interim coach because Jackson views him as the coach best suited to not only run the triangle offense he favors but also to manage the team using Jackson's long-held principles, as ESPN.com first reported earlier this month.
Rambis took over on an interim basis for the fired Derek Fisher on Feb. 8. At season's end, Jackson complimented Rambis for helping the Knicks run the triangle offense more effectively. In his most recent public comments on the coaching search, Jackson made it clear that he's fully committed to running the offense and will look mostly at candidates who have a prior relationship with him.