The pair appeared together in numerous films, including "The Lost Boys," "License to Drive" and "Dream a Little Dream." They also co-starred in the reality series "The Two Coreys," which ran for two seasons (2007-08).
"I was awakened at 8:30 this morning by my brother and sister knocking on my bedroom door. They informed me of the loss of my brother Corey Haim. My eyes weren't even open all the way when the tears started streaming down my face," Feldman said on his blog.
"I am so sorry for Corey, his mother Judy, his family, my family, all of our fans, and, of course, my son who I will have to find a way to explain this to when he gets home from school. This is a tragic loss of a wonderful, beautiful, tormented soul, who will always be my brother, family, and best friend.
"We must all take this as a lesson in how we treat the people we share this world with while they are still here to make a difference. Please respect our families as we struggle and grieve through this difficult time. I hope the art Corey has left behind will be remembered as the passion of that for which he truly lived."
Haim had long battled an addiction to drugs and police said they suspect his death was caused by an accidental overdose.
However, officials said they are awaiting toxicology test results before determining the cause of Haim's death at the age of 38.