Grayson made his first-class debut for Yorkshire in 1990 where he played for five years. Having been released in 1995, he joined Essex and was awarded his county cap in his first season, 1996. Grayson played for England in one day internationals in 2000, at the ICC knock out Competition. He was out for a golden duck, and his five overs went for 20 runs. He played his second ODI a year later, having been chosen for the squad to tour Zimbabwe.
Grayson retired from first-class cricket at the end of 2005, having scored 8,655 runs at 31.70, and taken 136 wickets at 44.39. In July 2007, he became the head coach at Essex, having previously played for, and coached, their second XI. The Cricketers' Who's Who 2011 stated "Grayson is a progressive coach with sound, modern methods to dealing with todays players. Approachable, reasonable, and quietly authoritative, his coaching style leans on his experiences as a Yorkshire player, and latterly as a canny left-arm spinping allrounder with the county he now coaches". He often talks on BBC Radio Essex during County Championship and CB40 games.