The move came on the second day of free agency, one day after Florida assistant general manager Randy Sexton had said that the chances of signing Leopold appeared "remote."
"I'm pumped to get it done," Sexton said Thursday. "We are absolutely ecstatic to have Jordan in Florida. ... I did think it was remote yesterday. That's one of the interesting things about free agency."
Leopold had his exclusive negotiating rights traded to the Panthers on Saturday for the rights to Bouwmeester, who signed a multiyear contract with Calgary on Tuesday.
Even though the Panthers didn't get a deal done with Leopold before he hit the open market, they were still able to sign him.
"Sometimes these things take longer than you would hope," Sexton said. "I think that at the end of the day, there was very genuine interest in Jordan's part to come to Florida."
Sexton and Leopold said the defenseman turned down longer-term offers and more money from other clubs to sign with the Panthers. The 28-year-old Leopold said he was looking forward to the opportunities he would have with Florida, and didn't think other interested teams were "the right fit for my family."
"Things didn't seem to work out," Leopold said. "As the day gets longer, weird things happen. (Sexton) happened to call at the right time and we were able to work something out."
Bouwmeester and Leopold have not been the only changes in the Panthers defensive corps this offseason. Florida, which lost defenseman Karlis Skrastins to free agency on Thursday, also announced that defenseman Clay Wilson signed a two-year contract.
On Wednesday, defenseman Ville Koistinen agreed to terms on a two-year deal with the club on Wednesday. Skrastins signed a two-year deal with the Dallas Stars.
"We're really pleased about our rebuilt defense," Sexton said. "We're mobile, we can get up the ice quickly."
Leopold, who has been traded four times, played in 83 games for the Flames and the Colorado Avalanche during the 2008-09 season.
The Minnesota native has played in 355 games in his NHL career and was a member of the 2006 U.S. Olympic team.