Canada, ranked eighth, will host Colombia in a World Group playoff at the Metro Halifax Centre from Sept. 12-14.
Joining Raonic is Frank Dancevic, Daniel Nestor and Vasek Pospisil.
Also headed to Halifax to round out Canada's extended squad is Jesse Levine, Adil Shamasdin and Brayden Schnur.
The Colombians, ranked 26th overall, plan to counter with Santiago Giraldo (32), Alejandro Falla (71) and doubles specialists Robert Farah and Juan Sebastian Cabal.
A 4-1 first-round loss to Japan at Tokyo forced Canada into the playoff, which it must win to remain in the World Group for 2015. A loss results in relegation to the Americas Zone Group I for the first time since 2011.
“A lot of milestones have happened in the careers of our players since the tie in Japan," Canadian captain Martin Laurendeau said in a Tennis Canada statement released Tuesday.
"And I think we are all looking forward to coming back together for Davis Cup and fighting to prove that we can be a perennial contender by keeping our spot in the World Group.”
Canadian Roots: Thornhill, Ont.
ATP Ranking: 6 in men's singles
Davis Cup: 5-1 in 2014
Highest-ranking Canadian in history. 47-13 record on ATP Tour in 2014. Only player this season to reach the quarter-finals or better in six Masters 1000 events. Won Citi Open at Washington, defeating Pospisil 6-1, 6-4 in final.
Canadian Roots: Niagara Falls, Ont.
ATP Ranking: 135 in men's singles
Davis Cup: 2002-14, excluding 2008 (injured)
Won Kosice Open, defeating Norbert Gombos 6–2, 3–6, 6–2 in final. 2-6 record on ATP Tour in 2014. Reached second round at Wimbledon, propelling him back into Top 100 for first time since 2009.
Canadian Roots: Vernon, Vancouver, B.C.
ATP Ranking: 46 in men's singles
Davis Cup: Playing in 10th tie since 2011
Ascended to career-high No. 25 ranking before suffering back injury. 20-18 record on ATP Tour in 2014. Reached first ATP final in Citi Open at Washington, losing 6-1, 6-4 to Raonic. Won men's doubles titles at Wimbledon and BB&T Atlanta Open with playing partner Jack Sock.
Canadian Roots: Toronto
ATP Ranking: 5 in men's doubles
Davis Cup: 1992-2014
Holds Canada's Davis Cup records for ties played (46), wins (46), doubles wins (31). Won mixed doubles title at 2014 Australian Open with playing partner Kristina Mladenovic. Also won men's doubles titles at Brisbane International, Apia International Sydney, Italian Open and Madrid Masters this season.
Laurendeau on Canada:
"With the support of a home crowd and in a new and exciting market, I know our team will be ready to go out there and work hard for a victory."
Laurendeau on Colombia:
"A very tricky team with talented players and they're looking to make their own history by advancing to the World Group for the first time."