Mr Nettles, 67, has brought dozens of wrong-doers to face justice as top TV cops Jim Bergerac and Tom Barnaby. The two long-running series, Bergerac and Midsomer Murders, have made the actor a household name and earned him the honour for services to drama.
Detective Chief Inspector Tom Barnaby will solve his last murder in Midsomer early next year before retiring after almost 15 years in the job.
Speaking after receiving the award at a Buckingham Palace investiture ceremony, the actor said: "I think it's absolutely wonderful, I cannot be more pleased. I don't really deserve it.
"People who get OBEs are people like firefighters and lifesavers - these are real-life heroes."
The actor also revealed that the Queen was a fan of DCI Barnaby.