The two additions offer similar skills to those of New Jersey Devils' puck-moving defenceman Paul Martin and rugged Toronto Maple Leafs' blueliner Mike Komisarek, who were both forced off the squad this week with injuries.
"These are both players who were prominent during the original picking of the team," said Team USA general manager Brian Burke during a conference call to announce the additions.
"Ryan Whitney is a good-size player with mobility and puck-moving skills and Tim Gleason a good-size defenceman with a hard edge to his game.
"These are two players who were alive right to the bitter end of the selection process, so they were guys who were knocking at the door, so we feel fortunate that we can add players without a significant decline in the pool."
Gleason has represented the US three times internationally, including at the 2008 world championships, and has five goals and 10 assists this season for the Hurricanes, who sit at the bottom of the Eastern Conference.
Whitney has four goals and 20 assists for the Ducks.
The US open the Olympic tournament on February 16 against Switzerland.