Corker is the ninth Republican vote for the treaty, joining Sens. Bob Bennett (R-UT), Johnny Isakson (R-GA), and Sen. Lamar Alexander (R-TN) who announced earlier today.
Sens. Richard Lugar (IN), Susan Collins (ME), Olympia Snowe (ME), Scott Brown (ME) and George Voinovich (OH) have also announced their support.
Corker's vote gives the treaty enough votes for ratification.
The Senate is expected to vote later today to end a GOP filibuster and cut off debate on START, with the final ratification vote coming later this week.