McDonnell began his law enforcement career as twenty-one-year-old graduate from the Los Angeles Police Academy in 1981. During his 28 years of work in the LAPD, he held every rank except Chief of Police and served as second in command to Chief William Bratton. He was considered a frontrunner for the position but Charlie Beck was appointed instead of him. While at the LAPD McDonnell was viewed as an ambassador who helped the department connect with Los Angeles' diverse communities and political leaders as Bratton's chief of staff and second-in-command. As a candidate for Chief in 2002, McDonnell presented a plan for community-based policing that was eventually adopted by Bratton and served as the foundation to overhaul and reform the LAPD. While working for the LAPD, he held a variety of assignments in patrol, detectives, vice, gang, organized crime, homicide and other divisions. In the 1990s as a commander, he gained attention for his efforts to revitalize the LAPD's senior lead officer program and to build the LAPD forerunner to the Compstat computer crime-mapping system along with helping implement the consent decree.
LBPD
In March 2010, McDonnell was appointed as the police chief of Long Beach, California, replacing former Chief Anthony Batts, who left to become the chief of the Oakland Police Department, over objections by some in the department who preferred a chief from the department. As police chief, McDonnell dealt with a large increase in officer-involved shootings and a 20% decrease in sworn officers from 1,000 to 800. McDonnell oversaw a 20% drop in violent crime and has been credited with dramatically improving community relations with the police, helping drastically reduce gang activity, and trying to improve racial diversity in the department. After McDonnell's election on November 4, 2014, Deputy Chief Robert Luna was selected to replace him to become the 26th Police Chief of Long Beach. Luna was considered a frontrunner for the position before McDonnell was appointed and became the department's first Latino police chief.
LASD
McDonnell has said he would work with district attorneyJackie Lacey to send some prisoners with mental health problems to psychiatric institutions rather than jail. McDonnell has stated that a new facility would be built to replace the dilapidated Men's Central Jail. He has expressed support for a civilian oversight commission to supplement the new inspector general in monitoring the department but has stated that he is still evaluating whether the inspector general should have subpoena power and access to personnel records. He was sworn in on December 1, 2014 and became the first person from outside of the sheriff's department to be elected to the office of Sheriff in over 100 years. Jim McDonnell was also the first incumbent sheriff in over 100 years to lose the position of sheriff. Alex Villanueva succeeded him following the November 2018 general election in California.
Elections
2014
;June 2014 ;November 2014
Dates of rank
Personal life
McDonnell is married to Kathy McDonnell. They have two daughters, Kelly and Megan.