Goals from Lewis Holtby and Klaas-Jan Huntelaar late in the first half turned the game around for the visitors after Kaiserslautern, who have not won in 16 consecutive games, had taken a third-minute lead through Rodnei.
Spaniard Raul then ended any lingering hopes the hosts may have had when he rifled in from 19 metres with an unstoppable left-footer for his 12th goal of the league season and Jefferson Farfan tapped in another nine minutes from time after a quick break involving Holtby.
"It would great if we could finish fourth this season," said Schalke coach Huub Stevens. "We said we wanted to get a quick third goal after the break and after Raul's superb goal everything was easy."
The win lifted Schalke, who will face Athletic Bilbao in the Europa League quarter-finals, to 50 points. They lie one behind third-placed Borussia Monchengladbach and 10 ahead of fifth-placed Bayer Leverkusen.
The top three Bundesliga finishers qualify for the Champions League group stage while the fourth team plays in the competition's preliminary round.
Kaiserslautern dropped five points off the relegation playoff spot with the future of coach Marco Kurz in doubt.
"If we want to stay up we have to play differently than we did today," Kurz told reporters. "Now we need to get back up and we will get back up."
In the only other Bundesliga game on Sunday, Europa League quarter-finalists Hannover 96 beat Cologne 4-1 - their first win in the last four league games - to move into seventh place and stay in the running for a European spot.
January signing Mame Diouf scored twice after goals from Lars Stindl and Jan Schlaudraff. Cologne's Kevin Pezzoni had briefly levelled just before the break.
Champions Borussia Dortmund protected their five-point lead at the top with a 1-0 win over Werder Bremen on Saturday with Bayern Munich in second place on 54 points after their 6-0 away demolition of Hertha Berlin.
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