King's Officer's affinity for wet tracks has come to the fore as the gelding produced a dominant finish to break through for his first Highway handicap win in seven attempts.

The Terry Robinson-trained gelding sprinted away late for a four-length win ahead of Attainment in Saturday's 1400m TAB Highway Handicap at Rosehill.

On a track rate a heavy 10, the five-year-old claimed his third career win and second on a bog track.

King's Officer is trained on the NSW south coast by Terry Robinson and was ridden by apprentice Koby Jennings whose two-kilogram claim saw the gelding carry just 56.5kg.

He has twice finished third in Highway handicaps, designated Saturday races for horses trained outside the metropolitan area.

"He's run some terrific races and thoroughly deserved to win one of these," Robinson said.

On a day where horses are routinely improving out wide on the track barrier 14 may have worked in his favour.

"He's drawn wide so many times and had to get so far out of his ground," Robinson said.

"But on this (wet) track that might have been the place to be."