Rolfe opened the scoring in the 13th minute with a well-placed left-footed shot from 18 yards out, signaling that Chicago was ready to bounce back from last weekend's 4-1 loss to Dallas.
Los Angeles, which broke its 12-game unbeaten streak last weekend with a 5-2 win over D.C. United and is hoping to avoid a third-straight absence from the playoffs, equalized in the 35th minute. League-leading scorer Landon Donovan sent Chris Klein down the wing with a nice looping pass and Eddie Lewis clipped Klein's cross into the goal with his left foot.
Blanco, the second biggest fan draw in MLS after Beckham, exploited the blundering of Galaxy keeper Josh Wicks and defender Troy Roberts to score in the 57th minute. The 35-year-old Blanco outpaced Roberts, 25, as they raced toward a through ball from Rolfe. When Wicks failed to handle the ball 15 yards outside his penalty area and Roberts fell to the ground, Blanco hurdled Roberts and stroked the ball into an empty net from 25 yards out.
Two minutes later, Blanco received a pass at midfield and relayed it to Gonzalo Segares with a clever back-heel pass. Segares sent the ball to the streaking Rolfe, whose 18-yard shot deflected of Wicks' right hand and into the goal. It was Rolfe's sixth goal of the season.
Donovan, who has scored 19 goals this season, squandered a golden chance in the 71st minute when he volleyed over the net from seven yards.
The win improved Chicago's record to 12-9-5 and keeps it in third place in the East, six points ahead of the New York Red Bulls.
The Galaxy (7-11-8) is tied for last place in the West on 29 points with San Jose, which has two games in hand.
"We played really well the other day and the confidence maybe was too high going into this game," Beckham said. "We need to pick ourselves up from this because we're running out of games now. We just need to start winning games, that's the biggest thing. It's easier said than done at the moment."
Blanco now has 5 goals and 8 assists for the Fire. Beckham has 5 goals and 9 assists for the Galaxy.
The pair joined MLS in 2007 as under the new Designated Player rule, which allows club owners to sign players for salaries above the league limit. Blanco's MLS career totals are: 37 games, 9 goals, 15 assists; Beckham: 28 games, 5 goals, 11 assists.
The game marked Chicago's the second sellout of the season at Toyota Park.
Chicago 3 Los Angeles 1. Goals: Rolfe (Thorrington) 13, Blanco 57, Rolfe (Segares 2, Blanco) 59; Lewis (Klein, Donovan) 35.
Los Angeles -- Wicks, Klein, Franklin, Roberts, Jazic, Beckham, Donovan Vanney (McDonald, 80), Lewis, Gordon (Vagenas, 63), Buddle (Jordan, 77).
Chicago -- Busch, Prideaux, Conde, Soumare, Segares, Mapp (Banner, 79), Thorrington, Blanco (Gutierrez, 89), Pause, Rolfe (King, 84), McBride.
Yellow cards: Chicago -- Soumare 72; Los Angeles -- McDonald 88, Roberts 90.
Referee: Alex Prus