"I want to tell you how excited I am to work with Mayor Lightfoot and continue the legacy of my close friend Eddie Johnson," Interim Superintendent Beck said.
Beck, 66, is the son of a former cop and a native of Long Beach, California. He served in the LAPD for 41 years and became chief in 2009 before retiring in 2018.
WATCH: Charlie Beck speaks after being named interim chief of Chicago police
"We wanted a leader with the specific values and record of accomplishment we need during this pivotal moment in our city's history," Mayor Lightfoot said. "Who can extend beyond simple crime reduction and expand to continuing our consent decree process and strengthening organizational efficiencies."
When Johnson first became superintendent in April 2016, Beck said he called him to offer him, "Whatever the LAPD has" and ended up loaning his chief of staff for over a year to Chicago to help.
"For the last several years, Chicago and Los Angeles have been partner cities in developing and implementing proven strategies to safeguard our communities and build community trust. Over that time, I got to know Superintendent Johnson and we've become very good friends and colleagues," Interim Superintendent Beck said. "I am truly privileged for the opportunity to now serve as Interim Superintendent of the Chicago Police Department and build upon the incredible work done by Superintendent Johnson and the dedicated police officers in Chicago."
Beck will work side-by-side with Johnson until the end of the year, a prospect the outgoing superintendent said is valuable.
"I do know Charlie Beck, he has been a friend and a mentor," Johnson said. "Back in 2016, when things were just spiraling out of control, I reached out to several other cities and he was one of them, and he has been a friend to me from that moment."
Beck was greeted by top brass in the department at CPD Headquarters and then headed into a meeting with other supervisors and staff. He then went to City Hall to meet with aldermen and city officials from other agencies that work with police.
He is considered a national leader on police reform, building community trust and using technology. During his tenure, Los Angeles police saw community trust go up and crime go down in the most violent parts of the city.
"In my last year as chief, the homicide clearance rate in South Bureau, which unfortunately has the highest homicide rate in the city, but the homicide clearance rate was 80 percent, higher than the rest of the city. That shows a level of cooperation that is caused by trust. Trust is not just one of the things in policing, it is the only thing."
Beck will be paid the same salary rate, $260,000 a year, but he said he has no interest in taking on the job permanently.
"That is a question for Mrs. Beck, and the answer was no," he joked, before turning serious. "You know what, no I would not. First of all, I think it's important to the process that I be absolutely honest with Chicago."
The next step is now in the hands of the Chicago Police Board, who will conduct a nationwide search for Johnson's permanent replacement and then present Mayor Lightfoot with three options she can choose from. That process is expected to take months.
WATCH: Eddie Johnson sits down one-on-one with ABC7 Political Reporter Craig Wall
Johnson says his eventual successor needs to be involved in the community, willing to talk to his or her critics and both advocate for and hold accountable rank-and-file officers.
Speaking to students at the University of Chicago Thursday night, Johnson could barely contain his emotions.
RELATED: Chicago Police Superintendent Eddie Johnson announces retirement
"And I love this department, so it's not easy, but mentally, I'm in a good place," Johnson said.
Earlier, joined by family, the 59-year-old Johnson said he'd thought about retiring for months. He said the ongoing investigation into last month's incident where he was found slumped over in his car had no bearing on his decision, citing a recent family trip to London.
"It made me feel normal and it made me feel how much I wanted to get that back," Johnson said.
RELATED: Cloud over Chicago Police Superintendent Eddie Johnson's final days
Mayor Lightfoot praised the career cop for his three decades' of service, including nearly four years as superintendent.
"Superintendent Johnson took on the challenge of reducing violence throughout our city and changing the culture within the CPD," Lightfoot said.
Johnson's last day on the job will be December 31. He said he plans to take at least a month off before deciding what's next. He said he's a high octane kind of guy, so he says there's no doubt he'll be doing something down the road.
The Los Angeles Police Department released a statement after the announcement saying, "The Los Angeles Police Department has worked closely with the Chicago Police Department for many years sharing innovative approaches to crime fighting, constitutional policing, and community engagement.
Former Chief of Police Charlie Beck was the architect for much of that work, and his appointment as interim Superintendent will ensure the momentum gained through this partnership is not lost.
"Current LAPD Chief Michel Moore said, "Beck is the ideal person to shepherd the Chicago Police Department through this next period. His vast experience with police reform, strategic approaches in reducing violent crime, and ability to guide and inspire rank and file police officers will be invaluable as the Chicago Police Department searches for a permanent superintendent."