Hudson came into the game with a 5.40 ERA this spring. He allowed six hits, struck out five and walked none.
"That's him, right there," Braves manager Fredi Gonzalez said. "His command on all his pitches was excellent."
Hudson threw 45 of his 65 pitches for strikes.
"Today was the biggest step I've made this spring," Hudson said. "My arm strength felt a lot better and that means a lot to all of my pitches."
Hudson will be making his third opening start for the Braves when he faces Philadelphia on April 1. He also drew the assignment in 2006 and 2008 after starting three openers previously with Oakland.
"It's an honor and a privilege to pitch on opening day with any club, especially with this team," Hudson said. "I feel that we have a lot of guy who were deserving of it."
The 37-year-old Hudson was 16-7 with a 3.62 ERA last year despite missing the first month while recovering from back surgery.
"Why not give it to the veteran guy?" Gonzalez said of picking Hudson over Kris Medlen, who was 9-0 with a 0.97 ERA after joining the Braves' rotation last season. "The opening day start is a special thing. They'll downplay it, but it's a special thing."
Nationals starter Dan Haren, though, continued to have some rough spots. He allowed eight hits and four runs in 5 1/3 innings and has a 6.05 ERA this spring.
Upton's homer leading off the sixth cleared the scoreboard in deep left-center field. It was his fifth homer of the spring and gave him 17 RBIs in 20 games.
"I thought that ball was never coming down," Gonzalez said.
Said Upton: "They all feel the same when I hit them. I don't know if that was one of my longest or not."
Haren gave up two singles following Upton's homer and was pulled after 90 pitches.
"I'm just kind of frustrated with the way it finished," Haren said. "I've just got to do a better job putting away hitters and I have to throw more strikes. But it was definitely an improvement from the last start."
CF Roger Bernardino returned to the Nationals after playing for the Netherlands in the World Baseball Classic and was 0 for 1 as a late-game replacement. ... Nationals closer Rafael Soriano had a root canal on Thursday, but is still expected to pitch in a game against the Tigers on Friday. RHP Stephen Strasburg is scheduled to start. ... LHP Paul Maholm, who hasn't allowed a run over 14 2/3 innings in his past three outings, will start for the Braves against the Phillies on Friday.