The 6ft 7in second row was outstanding in the Chiefs' successful campaign last year and picked up the coveted trophy when he led his side in the 37-6 demolition of the Sharks in the final.
His consistent, high class performances saw him pick up a string of accolades including nominations as one of three finalists for the Super Rugby Player of the Year at the 2012 New Zealand Rugby Awards, selection for the Super 15 Team of the Year and the Chiefs' award for Players' Player of the Year.
Because of his form throughout the Super Rugby season last year, the Chiefs skipper was also called into the All Blacks training squad.
The 29-year-old Clarke has turned out 57 times for the Chiefs and also captained Taranaki during the 2011 ITM Cup.
Born in Masterton, at the southern tip of New Zealand's North Island, Clarke initially made his mark with Canterbury and the Crusaders before moving to Taranaki in 2007.
He played a single season with the Hurricanes before joining the Chiefs, where his leadership credentials became apparent.
Clarke represented the Junior All Blacks in their 2009 IRB Pacific Nations Cup campaign, his debut coming against Samoa. He then started against Japan where he scored a try for the side.
Connacht Rugby CEO Tom Sears said: "We are absolutely delighted with this key signing - it is a major coup for Connacht.
"This is something we have been working towards for some time now and the fact a player of Craig's calibre has chosen to commit to Connacht is a clear sign of the progress we have made and our intent going forward.
"Our coaching staff are delighted to have Craig on board, he has all of the qualities we are looking for on and off the field and we have no doubt that he will be a major influence for Connacht in the seasons to come.
"With a three-year deal Craig has shown he really believes in what we are doing and the potential we have.
"After leading the Chiefs to the Super 15 title last season Craig certainly wasn't short of options - he has chosen Connacht because he wants to be a part of what is happening here.
"Our squad recruitment and retention programme for next season has gone very well. We still have a number of areas we are working on but this is a key part of the plan that has fallen into place."