
McKilwee, who also beat London's Graham Hedger, finished the course in two hours and 46 minutes.
He said: "There are a couple of tough climbs that take it out of you but I managed to hang on."
The half marathon saw some local success with Manx Harriers' Ed Gumbley winning the men's race and Hannah Howard taking the ladies title.
There was disappointment for local favourite Lambden who took the lead after 17 miles but faded in the final stages to finish third, in a time of 2'54.
Murray said: "I made one of the most basic mistakes in marathon running by going too fast too soon and not keeping a consistent pace.
"I ended up going through the last five miles of hell."
But there was some consolation as he picked up his third Isle of Man championship title, a competition for Manx runners taking part in the marathon.