Hick, 93 not out overnight in a Second Division County Championship match against Northamptonshire, completed the feat in front of Worcestershire's home fans at New Road on Thursday.
It didn't take long for Hick to add the seven required runs he needed for his hundred.
A flicked single off his legs against Australia seamer Matthew Nicholson took him to the landmark in 182 balls with one six and 11 fours.
Hick's total of 130 first class hundreds means he has now moved into eighth-place in the all-time list, overtaking former England captain and opening batsman Sir Len Hutton.
England legend Sir Jack Hobbs heads the all-time list with 197 first-class centuries.
Worcestershire's director of cricket, Steve Rhodes, said: "Graeme has achieved something that not many people can dream of doing. His hundredth hundred is a true reflection of what he has done for Worcestershire County Cricket Club over the course of his career.
"I consider myself extremely fortunate to be amongst those who have watched Graeme's successes unfold and it has been fantastic to watch him score many of his hundreds over the years," the former Worcestershire and England wicket-keeper added.
"We all have great memories. Perhaps the thing I most remember from his heyday was his strength.
"We would watch from the balcony as, time after time, he would hit a yorker straight back past the bowler for four: something incredibly difficult to do and which gave rise to the dressing room saying 'You can't bowl there to Hicky!'
"We all whole heartedly congratulate him on reaching this significant landmark."
The other seven players to have scored a century of centuries for a single county, all of whom played for England, are: Hobbs (Surrey, 144 centuries), Phil Mead (Hampshire, 138), Frank Woolley (Kent, 122), Patsy Hendren (Middlesex, 119), Walter Hammond (Gloucestershire, 113), Herbert Sutcliffe (Yorkshire, 112) and Geoffrey Boycott (Yorkshire, 103).
Unlike many of the illustious names on the list of leading centurions, the 40-year-old Hick - born in what was then Rhodesia and now Zimbabwe - did not enjoy a highly successful Test career.
He was forced to serve a residential qualification period before making his England debut in 1991.
Repeatedly dropped and recalled by England, he was famously labelled "a flat-track bully" by New Zealand coach John Bracewell.
Hick played the last of his 65 Tests against Sri Lanka at Kandy in 2001, finishing with 3,383 runs at a modest average of 31.32 with six hundreds.
But it is unlikely any contemporary or future player will surpass his county record.
Since Hick made his Worcestershire debut in 1984, there has been a huge reduction in the number of first-class fixtures.
Meanwhile the accompanying growth in the Test programme has led to England batsmen making fewer and fewer appearances for their counties, with the national team management increasingly ordering to them rest between international matches.