Sheehey, a four-year player at Indiana, went undrafted in Thursday's NBA Draft, but he agreed to play for the New York Knicks in Summer League competition.
The news was broken by Sheehey's high school coach, Adam Ross, on Twitter.
Sheehey worked out for 10 teams before the draft, including the Knicks.
The Knicks begin summer league play on Friday, July 11 at the Cox Pavilion in Las Vegas. Several games will be broadcast live on NBA TV.
As a senior at Indiana, Sheehey averaged 11.4 points and 4.0 rebounds per game and shot 33 percent from 3-point range.