The Durham quick's match-winning nine-wicket haul in the fourth and final Test against the West Indies took him above Sri Lankan off-spinner Muttiah Muralitharan and South Africa's Shaun Pollock.
Harmison is the first England bowler to top the list for more than twenty years.
England have won seven straight Tests in a row, and all four of their leading bowlers appear in the top twenty. Aside from Harmison, the other three are Ashley Giles, Andrew Flintoff and Matthew Hoggard.
Spinner Giles and all-rounder Flintoff have both climbed over twenty places since May.