The 31-year-old McKee signed a four-year, $16-million free agent contract in 2006 and was due $4 million for next season. The Blues are responsible for two-thirds ($2.64 million) of McKee's salary, which will be spread out the next two seasons.
McKee, known for his shot-blocking ability, played in 158 games during an injury-marred tenure in St. Louis. He had three goals and 14 assists in three seasons.
"It's not something I expected, especially after my most productive season in St. Louis," said McKee, who will become a free agent. "I understand they had a decision to make and I was one of them.
"The bottom line is, I didn't fit in their depth chart and my salary was probably a hindrance to their payroll."