Los Angeles acquired the veteran infielder on Sunday afternoon for Minor League right-hander Luis Garcia and a player to be named. The trade was made official following the Nationals 2-1 loss to the Cardinals on Sunday afternoon.
"I'm happy because I'm going to L.A. and that team is in first place," Belliard said. "But I'm sad because I am going to leave a lot of friends. I've been here for the last three years and I made a lot of friends.
"This late in the year, this wasn't in my mind."
Belliard was hitting .247 with five home runs and 22 RBIs for the Nationals but has been hot of late. In 34 games since the All-Star break, the right-handed-hitting Belliard is .325 with five doubles, three home runs and 14 RBIs.
"It's kind of two-fold," said Nationals interim manager Jim Riggleman. "Ronnie played really good for us. We've played pretty good baseball since the All-Star break and he's been a part of that. On the other side of it, we get to keep an infusion of young players coming in and Ronnie gets to go play in a pennant race. I think it's a win-win for everybody."
Belliard didn't get much playing time early this season when he hit only .184 in the first half, but as his opportunities have increased, so have his results.
"I'm playing more," Belliard said Saturday. "I just wasn't playing before. Now I got myself in the lineup more and I'm doing better.
"When you're not playing and not doing anything and then you find yourself in the lineup all of a sudden, it's hard to prepare. When they give you playing time, you know you are able to contribute to the team."
Belliard was traded from the Cleveland Indians to the Cardinals during the 2006 season and has been with the Nationals since 2007.
He is a career .274 hitter with 107 home runs and 565 RBIs in 12 Major League seasons.
"It's a compliment," Belliard said. "Now I have a chance to win another [World Series]. I helped the Cardinals in 2006 with my defense and some lucky hits that I got in the playoffs. Hopefully I can do that in L.A. That's why they traded for me."
Belliard flew with his former team to San Diego Sunday evening where the Nationals will open a three-game series with the Padres on Monday. He will join his new team a few hours north in Los Angeles on Monday.
Garcia, 22, had a 2.92 ERA in 34 appearances in the Low-A Midwest League but wasn't considered one of the Dodgers' top 30 prospects before the season by Baseball America.
B.J. Rains is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.