"Professionally it's been a good move for me and on the personal side my family are enjoying our time here and are very happy to remain for the immediate future.
"With the contract side of things now settled, I'm looking forward to what I believe will be a very exciting second part of the season and hoping to play my part in helping Munster achieve success on the field."
Munster coach Tony McGahan expressed his satisfaction when he said: "I'm delighted we're retaining the services of a player of Doug's proven calibre.
"Doug's contribution to the squad and management, on and off the field, has been central to our success since he arrived here two years ago.
"So, it will be very advantageous to have a player of his quality and experience to call on. It's great news for Munster Rugby."
Howlett touched down at Cork International Airport in December 2007 and just two weeks later made his debut in the Heineken Cup game against Clermont Auvergne at the Parc des Sports Marcel Michelin.
He scored the first of his 12 tries to date in the 42-6 win over Ulster at Musgrave Park, his first Heineken Cup try in the memorable win over Gloucester at Kingsholm and capped a great first six months with Munster by helping the province lift their second Heineken Cup title.
A model of consistency throughout his time with Munster, in his first full season (2008/09), Howlett played in 22 of Munster's 25 competitive games.
This term, he has played in 13 of Munster's 17 games, with an injury sustained in the Heineken Cup game against Treviso ruling him out of two of those fixtures.