The 52-year-old said she felt "deeply honoured and proud" to get the award.
"To be included in the distinguished and diversely talented company of the other Companions of Honour, especially as a female writer, is a particular privilege," she said in a statement.
Membership of the Order of the Companions of Honour is a special award held by only 65 people at any one time.
Established in 1917 by George V, it recognises services of national importance.
Rowling, whose first name is Joanne, was awarded an OBE in 2001.