Bartelstein said in a phone interview that Smith had signed a one-year, $3.3 million contract with New York.
The Knicks used their tax payer's exception to sign Smith, who averaged 9.7 points, 5.8 rebounds and 0.9 blocks per game in 31 games last year for the New Orleans Pelicans.
Smith's season was cut short due to knee surgery.
The seven-foot Smith shot 46 percent from the field in 27 minutes per game last season before being sidelined for the year after undergoing surgery in mid January.
Smith's signing bolsters the Knicks' front line. New York had just four players who play power forward or center under contract before adding Smith.
The Knicks are over the salary cap and can only offer free agents the veteran's minimum exception for the rest of the offseason.