The stars play a couple on the US TV drama, and were said to have been dating since April.
But the 23-year-old blonde beauty has now taken to her Twitter page to set the record straight, reported Contactmusic.
"Hilarious. Although I do love you Tyler," Benson posted.
Benson and Blackburn first sparked speculation of an off-screen relationship when they were spotted holding hands and cuddling up to one another at the Coachella music festival in California in April.