Skiles also hired former NBA players Lionel Hollins and Joe Wolf.
"I'm excited to be able to assemble this strong coaching staff in Milwaukee," Skiles said in a statement. "Jim, Lionel, Kelvin and Joe all bring experience to the Bucks bench, as well as diverse coaching skills."
ESPN.com reported on May 2 that Sampson had agreed to join Skiles' staff.
Sampson brings some baggage to his NBA job.
He resigned as Hoosiers coach on Feb. 22 and accepted a $750,000 buyout after an NCAA report charged him with five major NCAA rules violations.
Sampson took the Indiana job in March 2006 and two months later was penalized by the NCAA for making 577 impermissible phone calls between 2000 and 2004 while coaching Oklahoma.
The second wave of charges emerged last October when a university investigation found Sampson and his staff made more than 100 impermissible calls while still under recruiting restrictions. Sampson also was said to have participated in at least 10 three-way calls, another violation of the NCAA's punishment.
At the time, Indiana athletic director Rick Greenspan called the violations secondary, imposing a one-year extension of the NCAA's recruiting restrictions and pulling a $500,000 raise for Sampson. The Hoosiers also took away one scholarship for the 2008-09 season.
However, an NCAA report released Feb. 13 by Indiana said Sampson provided false and misleading information to investigators from the university and the NCAA, failed to meet the "generally recognized high standard of honesty" expected in college sports, and failed to promote an atmosphere of compliance.
Sampson has since been replaced at Indiana by Marquette coach Tom Crean.
Boylan played at Marquette, winning an NCAA title in 1977, and spent four seasons on the Bulls' staff. After Skiles was fired as head coach in December, Boylan replaced him on an interim basis for the remaining 56 games.
Hollins, a 10-year NBA veteran, has been an assistant coach with Phoenix; an assistant and interim head coach with Vancouver; and an assistant with Arizona State. He was drafted sixth by Portland in 1975 and voted to the All-Rookie First Team. He won a title with the Trail Blazers in 1977.
Wolf averaged 4.4 points and 3.3 rebounds in his 11 seasons in the NBA, including the 1996-97 season with the Bucks.
Bill Peterson has been retained from last season's coaching staff.
Information from The Associated Press was used in this report.