The Royals obtained left-hander Ryan Buchter and right-handers Trevor Cahill and Brandon Maurer in exchange for left-handers Matt Strahm and Travis Wood, minor league infielder Esteury Ruiz and cash considerations.
Kansas City also recalled left-hander Brian Flynn from Triple-A Omaha and designated right-handers Al Alburquerque and Luke Farrell for assignment.
The Royals (50-47) entered Monday night's action trailing the AL Central-leading Cleveland Indians by 1 1/2 games after winning five consecutive contests.
Maurer, the 27-year-old closer for the Padres this year, converted 20 of his 23 save opportunities, including 15 in a row since May 28. The five-year major league veteran has a 1-4 record and a 5.17 ERA in 42 appearances this season.
Buchter, 30, has pitched in 42 games in relief this year for the Padres. He is 3-3 with one save, a 3.05 ERA and 48 strikeouts. Last year, he went 3-0 with a 2.86 ERA in a career-high 67 appearances for San Diego.
Cahill, 29, made 11 starts for the Padres this year and had a 4-3 record with a 3.69 ERA and 72 strikeouts. Last season, the nine-year veteran pitched in 50 games for the World Series champion Chicago Cubs and had a 4-4 record with a 2.74 ERA. He has a 73-79 career record with a 4.03 ERA.
Strahm, 25, was 2-5 with a 5.45 ERA in three starts and 24 games for the Royals this year. He has a career record of 4-7 with a 3.81 ERA in 45 appearances for the Royals.
Wood, 30, also was with the Cubs during their championship season a year ago, when he went 4-0 with a 2.95 ERA in 77 regular-season games and 1-0 in the postseason with a 2.84 ERA. This season, he was 1-3 with a 6.91 ERA in 28 games, including three starts, for Kansas City. Wood's career record is 44-55 with a 4.13 ERA in eight seasons with the Cincinnati Reds, Cubs and Royals.
The 18-year-old Ruiz has seen action in 21 games for the Arizona Rookie League Royals this year. He has a .419 batting average with 10 doubles, six triples, three home runs, 23 RBIs, 22 runs scored and nine stolen bases. The Dominican Republic native signed with the Royals as an international free agent on July 3, 2015.