The Canadian team announced during Friday's 4-1 win over Belarus that Hamhuis will join the team Saturday in Stockholm.
Hamhuis and the Vancouver Canucks were swept in the first round of NHL playoffs by the San Jose Sharks.
Hamhuis played in four straight world championships for Canada from 2006 to 2009. He was a member of the last Canadian team to win world championship gold in 2007.
He also won silver medals in 2008 and 2009 and the second time under current head coach Lindy Ruff.
"I'm happy to help," Hamhuis said before departing Vancouver. "It's been a great experience over the last four years that I've been playing (at worlds).
"There's been a real camaraderie with teammates and the players you get to meet over there. I've made a lot of friends there that I still keep in touch with, and teammates that are in touch."
The 30-year-old from Smithers, B.C., has five goals and nine assists in 36 career world championship games. He also wore the Maple Leaf at world junior championships in 2001 and 2002 and won bronze and silver respectively.
He was Vancouver's top producer from the blue-line this season with 24 points in 47 games.
"It's giving us a really good veteran player that has played against every top opponent in the league," Ruff said following Friday's game.
"We just think he's a great two-way player that maybe in some tougher situations and tougher games can supply us with some real good play."
The addition of Hamhuis increases Canada's roster to 23 players, including eight defencemen. Countries are allowed to a maximum of 25.
Canada (4-0-1) concludes the preliminary round against the Czech Republic and Slovenia on Sunday and Monday respectively. The top four countries in each pool of eight qualify for the quarter-finals. Canada has lost in the quarter-finals three straight years.
The Montreal Canadiens have also been eliminated from the NHL's first round. Ruff did not say whether more players will join Canada in Stockholm.
"There's been some discussions. There's been no conclusions to any of those discussions yet," he said.
"To this point, the players have played very hard and played well. To dislodge one of them at this time of the tournament or even if you get later on in the tournament for a player who comes over and plays one game, I think sometimes it could be tough on team chemistry. We've talked about those things.
"In Dan's case, he's getting here early enough."
Three Canadian defencemen — Justin Schultz, Brenden Dillon and T.J. Brodie — are representing Canada for the first time in their careers in this tournament. Only Luke Schenn and Stephane Robidas had played in a previous men's world championship.
Schultz has seen Hamhuis a few times this season when his Oilers faced the Canucks.
"He's a great overall player, moves the puck well and obviously real solid defensively," Schultz said. "We're happy to have him and he's going to improve our team for sure."
The arrival of Hamhuis will mean less ice time for some defencemen.
"We're honestly not worried about ice time here," Schultz insisted. "We're happy with whatever we get. We're just going to try and help the team win and he's going to be a big part of that."
Canucks forwards Daniel and Henrik Sedin and defenceman Alexander Edler are joining Sweden (3-2-0). They're expected to be in the lineup for Sweden's final preliminary-round game Tuesday against Denmark.
— Monte Stewart in Vancouver contributed to this story.