The Dodgers' second extra-inning win of the week pushed the team's record to 5-8 in bonus frames. At 12 innings it tied for the longest game of the year for the Dodgers, and at four hours, 39 minutes was the club's third-longest game of the year.
Ramirez hadn't homered since June 17, though he was hitting a still-productive .307/.418/.387 in the 91 plate appearances and 25 games since, entering Saturday night.
Including the home run - the first walk-off home run in Ramirez's career - Ramirez was 3-for-5 on the night.
"So long curveball, so long ballgame," said Vin Scully on the SportsNet LA television broadcast.
The home run came in Parker's second inning of work. He allowed a base hit to Dee Gordon, who moved into scoring position with his 51st stolen base of the season, still tops in the majors. Justin Turner, making his first start at first base this season, followed with a walk to setup Ramirez for his heroics.
Jamey Wright pitched two scoreless innings - the 11th and 12th - with a pair of strikeouts for the win. After a rough patch surrounding the All-Star break, Wright's last four appearances have been scoreless, with six strikeouts and one walk in 5⅔ innings during that span.
Chris Coghlan doubled with one out in the first inning against Hyun-jin Ryu, then scored one out later on a single by cleanup hitter Starlin Castro to open the scoring.
The Dodgers were kept mostly in check for Tsuyoshi Wada for nearly six innings, but the left-hander found trouble in the fourth inning. Ramirez led off the frame with a walk, then Matt Kemp hit one into the seats for a 2-1 lead.
Kemp entered the week with no home runs against left-handers this season, but now has two long balls versus southpaws.
Scott Van Slyke, a lefty masher in his own right, followed with a double, putting the Dodgers in business to add to their lead, but he was stranded on third base. In part thanks to Drew Butera getting intentionally walked with two outs, leaving Ryu to strike out to end the threat.
It was the first intentional walk ever received by Butera, a .183/.238/.265 career hitter.
The Cubs threatened all night against Ryu, putting runners on base in every inning but the fourth against him, but the left-hander struck out six in his seven innings and got a little help from his friends. Ryu got double plays in both the fifth and sixth innings.
But up 2-1 trying to squeeze an extra inning out of Ryu against the bottom of the order, manager Don Mattingly got burned in the seventh. A one-out single by Junior Lake was cashed in when Arismendy Alcantara doubled off the wall in right center field to tie the game.
Ryu ended up allowing two runs in seven innings, scattering nine hits, with six strikeouts and a walk. He has lasted seven innings in four of his last seven starts, and has walked two or fewer batters in 18 straight starts.
In his first 19 major league starts Ryu walked 41 batters. In his last 34 starts, including the playoffs, Ryu has walked 34 batters.
Brian Wilson pitched a perfect 10th inning in what was easily his best outing of the season. Wilson struck out the middle of the Cubs' batting order - Anthony Rizzo, Castro and Justin Ruggiano - on 13 pitches. The right-hander has struck out five consecutive batters dating back to Friday night.
The Dodgers go for the series win on Sunday afternoon, with Josh Beckett on the hill facing old friend Edwin Jackson for Chicago, making just his third Dodger Stadium start in nine seasons since he was traded away.
Home runs: Matt Kemp (12), Hanley Ramirez (12)
WP - Jamey Wright (4-2): 2 IP, 2 hits, 1 walk, 2 strikeouts
LP - Blake Parker (1-1): 1⅔ IP, 2 hits, 3 runs, 1 walk, 3 strikeouts