The 25-year-old forward was a restricted free agent and avoided a salary arbitration hearing scheduled for Thursday. He was traded to the Bruins by New Jersey Devils on July 13 for forward Erik Haula and had an NHL career-high 36 points (15 goals, 21 assists) in 70 games last season.
"If everything goes well, they know that I want to stay in Boston for a long time so I think it was more the focus on just staying here for one year and focusing on this season," Zacha said Tuesday "… I think I can help them for next season and just trying to get as best of a team as possible so we can all play. It's all about winning for us next season. I think it was a good deal."
General manager Don Sweeney said the Bruins were comfortable with a one-year contract.
"Certainly explored longer-term deals," he said Wednesday. "I think as an organization we've done a pretty good job of targeting players that we've acquired and then being able to extend, whether that's right away or down the road. Pavel's a guy we've indicated that we'd like to continue to talk and we can't do that until later in the year, but we will hopefully find common ground there."
Selected by New Jersey with the No. 6 pick in the 2015 NHL Draft, Zacha has 179 points (69 goals, 110 assists) in 386 regular-season games, all for the Devils, and no points in five Stanley Cup Playoff games.
"I'm just happy to be on a team that's going to be in the race and in a playoff run," Zacha said. "That's something that I wasn't part of the last six years. So just being part of this culture and trying to learn from it and just whatever position I'm going to get to play, I'm excited to help the team. … We have good players on paper, we just have to put it together and play as a team."
The Bruins also signed forwards Patrice Bergeron ($2.5 million) and David Krejci ($1 million) on Monday, each to a to one-year contract. Bergeron is returning for his 19th season in the NHL. Krejci played last season in his native Czech Republic after playing for Boston for 15 seasons (2006-21).
"We talked about with my agent and Boston, we made a decision on just focusing on this one year, bringing guys like Bergeron and Krejci, having a big chance of having a good year as a team and I think that was the biggest thing from both sides, just focusing on one year," Zacha said.
Along with Zacha and Krejci, the Bruins have three other players from the Czech Republic on the team: forwards Tomas Nosek and Jakub Lauko and defenseman Jakub Zboril.
"I watched [Krejci] a lot," Zacha said. "He's very, very skilled two-way center so that's something you look up to and try to learn from. I'm just really excited that he decided to come back and play here. Having five Czech players on a team doesn't happen that often so it's exciting for me."
Zacha, who can play center or wing, said he'll play wherever the team needs him.
"I played the last two three seasons kind of both," he said. "I think I played on a wing a little bit longer the last two seasons than I did usually, so I'm used to wing and I played there probably 75 percent of my last two seasons. … I think with where the spots are on the team, I think the biggest thing for me is I can play both and I can be used in both. Where I see I can fit in is probably going to be more on the wing this season. But I leave the decision to my coaches there."
NHL.com staff writer Amalie Benjamin contributed to this report