Outgoing NASA Commander Kevin Ford, who has held the role since November 2012, passed responsibility for the Station to Hadfield during a transfer-of-command ceremony at 5:10 p.m. ET.
Expedition 34 will end tomorrow when Ford and his crewmates undock from the Station.
"[Hadfield] has a vision for [Expedition] 35. He knows what's going to happen," Ford said from the ISS. "He's really a people person. He's out there, he shares things with everybody. He's a uniquely talented person on the planet and he's now a uniquely talented person off the planet."
Hadfield arrived at the Station in December, where he has been conducting experiments and sharing his experiences on social media.
Ford played the Canadian national anthem before ceding control, pointing out that Hadfield would be the first Canadian commander of the ISS. He will also be the first commander who is neither from NASA nor the Russian Federal Space Agency.
"We're very proud of Chris. We're very proud of Canada as our partner in this International Space Station," Ford said. "Canada has made a great contribution, just like so many of the other [international] partners have."
Hadfield spoke briefly before officially accepting command. "It's a huge honour and a privilege for me…but also [for] all my co-workers at the Canadian Space Agency and my entire country."
Hadfield will run the Station along with five other crew members. He'll return to Earth in mid-May.
The Queen congratulated Hadfield earlier Wednesday. "Our thoughts and best wishes are with him and the entire crew, as are our prayers for an eventual safe return to family, friends and fellow Canadians," she said in a statement.
Prime Minister Stephen Harper also expressed well wishes for Hadfield in a statement: "Today, on behalf of all my fellow citizens, I would like to congratulate our very own space pioneer, Chris Hadfield…His pursuit of excellence in his field and his achievements in space are a tremendous source of national pride and can most aptly be described as stellar."