O'Toole is to join the Championship club on 1 March from London Irish, where he has been commercial director for the past 18 months.
He will replace Charles Cameron, who left in February after only nine months in the post, prior to the Warriors' relegation from the Premiership.
"Jim made a significant contribution to our commercial operation," said Irish executive chairman David Fitzgerald.
O'Toole, who initially joined Irish as a consultant, has over 25 years of experience in sports marketing, having worked on projects as diverse as powerboats, professional sailing and football's Premier League.
Warriors chairman Anthony Glossop, who has served as acting chief executive for the past 10 months, said: "Jim has a wealth of very relevant experience that equips him well to provide a leadership role in taking the club forward."
Worcester are currently second in the Championship table under Dean Ryan, having not lost since the first day of the season. Their 12-match winning run has also seen them qualify for the quarter-finals of the British and Irish Cup.
Worcester Warriors have appointed Jim O'Toole as their new chief executive.