The king will stay at the royal residence during the day but will return at night to the hospital for a few days, the daily Aftenposten reported.
"I have been in decent shape for a long time and have been conscious throughout. Today I feel very good," King Harald said.
The king said he is in recuperative training after two operations, one to replace a defective heart valve and the second to drain fluid from around the heart.
A medical team said the king's condition is highly satisfactory.