The general manager was suspended for five weeks, beginning July 17, following his DUI arrest on July 4. The team also fined Keim $200,000.
Wednesday was the first day the GM was eligible to return to the team.
"For the past 50 days, I've replayed over and over in my mind what would I say or how could I apologize in a way that people would understand or forgive me for my inexcusable actions," Keim said upon his reinstatement. "And the truth is there is nothing I can say that would make what I did right. In fact, taking ownership and my behavior going forward will ultimately define me as a man. I do want to take this opportunity to personally apologize to our fan base, the entire Cardinals organization and most of all my family."
Keim was initially arrested on July 4 on suspicion of driving under the influence in Chandler, Arizona. He pleaded guilty to an extreme DUI charge, which is defined as blood alcohol content of .15 or above. Keim's BAC was .193, according to a Chandler Police Department report.
During his suspension, Keim was prohibited from making contact with the team. The GM was also ordered to complete counseling and evaluation, in addition to a DUI education course, and take part in DUI awareness and education programs before he was allowed to return to work.
"Over the past five weeks, I've had quite a bit of time to reflect, which has put a lot of things in perspective for me," Keim said. "I've hurt a lot of people in this process. In fact, after the reports came out, my 12-year-old son was texting with his buddy and he said, 'They keep showing your dad over and over again on TV.' I'm so sorry he's had to go through that. And my son said, 'I'm not and you shouldn't be doing it.' My son was right. I don't think there's any feeling that's worse than feeling like you let your children down."
The GM must get back up to speed quickly as the Cards' season kicks off in just 19 days away.