Billy Gardell as Officer Michael "Mike" Biggs, a Chicago Police officer attempting to lose weight. He doesn't appear to be a deep thinker, but he's good-hearted and humorous. He often caves in to his mother's demands, much to Molly's dismay, but his relationship with Molly has made him much more independent.
Melissa McCarthy as Molly Flynn, a fourth-grade teacher at Walter Payton Elementary School, also attempting to lose weight. She is sweet, happy, intelligent, and caring. She is the rational member of her family, but is known to have a quick temper and has built up much debt from lavish shopping and traveling. Many students still call her Miss Flynn. She quits her teaching job in Season 4 to become a writer.
Reno Wilson as Officer Carlton "Carl" McMillan, a Chicago Police officer and Mike's partner and best friend. He tends towards self-pity, owing to his mother abandoning him. He lived with his grandmother for a long time until she made him move into his own apartment. He struggles in relationships with women and is depicted as lonely. He is a big fan of soul and gospel music and openly dislikes bluegrass. In Season 2 he had a steady relationship with Christina (Holly Robinson Peete), a single mother with a young son, but in Season 3 Christina broke up with Carl to try to work things out with James, her famous football-player ex-husband, her son's father. As of the end of Season 4, Carl is in a relationship with Victoria.
Katy Mixon as Victoria Flynn, Molly's dimwitted, kindhearted, party-girl sister who is often high on marijuana. She is employed as a funeral-home beautician. She likes to have fun and sleep around, frequently with married men; but as of the end of Season 4 she is in a relationship with Carl.
Swoosie Kurtz as Joyce Moranto, mother of Molly and Victoria. Widowed when her daughters were young, she began dating Vincent Moranto in Season 1. She is very modern and attempts to stay youthful; she also drinks heavily and has a hair-trigger temper. As of the Season 3 episode "Thanksgiving Is Cancelled", she is married to Vincent.
Nyambi Nyambi as Babatunde bka Samuel, a sarcastic waiter at Abe's, the restaurant where Mike and Carl eat. He is also a close friend to Mike, Carl, and eventually Molly. He is from Senegal and often refers to the suffering in his home country, so he cannot easily sympathize with his restaurant patrons' "petty" problems. He and Carl became roommates in Season 3. In Season 5, Samuel's real name is revealed to be Babatunde when he becomes the new owner of Abe's Diner, renaming it Abe's Hot Beef.
Louis Mustillo as Vincent "Vince" Moranto (episode 14-present, recurring previously), Joyce's on/off boyfriend, then fiance', now husband and Molly and Victoria's stepfather, and Mike's stepfather-in-law. A widower, he tends to be flirty, chauvinistic, and sarcastic. A high-school dropout, he's not the most intelligent, but he cares deeply for Joyce and has shown fatherly care toward Molly and Victoria—despite having met Molly after being set up on a blind date with her, and his constant comments about Victoria's "rack." He once married a much-older, very unpleasant woman from whom he fled after borrowing $2,000; he didn't officially end this marriage until the truth came out and Joyce kicked him out of her house until Mike convinced the "wife" to sign divorce papers in exchance for $5,000...and a sharp kick to Vince's nuts.
Rondi Reed as Margaret "Peggy" Biggs (episode 15–present, recurring previously), Mike's mother. She is very controlling and traditional, as well as grumpy and cranky. She often refers to her ex-husband Jack leaving her and running away to Florida with a prostitute. Peggy is also very fussy over her dog "Jim" (a Brussels Griffon mix), whom she treats more like a son than a pet. In Season 2 Peggy began working as a lunch-lady at the elementary school where Molly teaches. In Season 3, she starts dating a CPD Captain who is Mike's supervisor.
Cleo King as Rosetta McMillan (episode 5–present, guest previously), Carl's grandmother. She is very traditional and has professed deep love for her grandson, but is outwardly annoyed by Carl's behavior and made him move out in Season 3, saying she still loves him and looks forward to him visiting but wants him to finally become a responsible adult on his own. She has a big heart and treats Mike, who calls her "Nana", like a second grandson. She often gives Mike and Carl advice (mostly regarding relationships with women). She once recalled that when Carl was young he could quote the entire speech of Martin Luther King, Jr. as well as every episode of The Dukes of Hazzard.
David Anthony Higgins as Harry (season 3-present, recurring previously), a friend of Mike and Molly's who attends the same Overeater's Anonymous meetings. He is nice but socially awkward and tends to say whatever he is thinking, even thoughts that make him seem pathetic. He was shown to have an almost-obsessive crush on Victoria; when she finally kissed him in Season 3, he realized that he is gay.
On May 13, 2010, CBS placed a series order on Mike and Molly. On May 15, 2011, Mike and Molly was renewed for a second season. On March 14, 2012, CBS renewed Mike & Molly for a third season, which premiered on September 24, 2012. CBS pulled the third season finale, titled "Windy City", from its show of May 20, 2013. The episode featured a tornado descending on Chicago, and would have been broadcast the same day as the 2013 Moore tornado. The episode was rescheduled for May 30, 2013.
On March 27, 2013, CBS announced that Mike & Molly would return for a fourth season during the 2013–2014 television season. On May 17, 2013, Mark Roberts stepped down from showrunner duties to focus on other projects. Al Higgins replaced him for Season 4. The series received a 22-episode order from CBS for its 4th season. The show's fourth season premiere took place on November 4, 2013 at 9:00 pm ET/8:00 pm CT, in the time slot vacated by 2 Broke Girls when it moved to 8:30 pm ET/7:30 pm CT, replacing the canceled sitcom, We Are Men. Following the breakout feature film success of McCarthy (Identity Thief, The Heat), Lorre intends for the show to more prominently feature Molly in season 4. In promos leading up to the season 4 premiere, CBS billed the series as The New Mike & Molly. Though the cast and setting remains essentially the same, the "new" refers to Molly quitting her teaching job and pursuing a career as a writer.
On March 13, 2014, CBS announced the fifth season renewal of Mike & Molly. CBS did not place the show in a timeslot when it unveiled its initial 2014-15 schedule. The fifth season began airing December 8, 2014.
Casting announcements began in February 2010, with Katy Mixon and Reno Wilson being the first actors cast in the series. Mixon portrays the role of Victoria, Molly's sister, while Wilson portrays Carl, Mike's partner.Billy Gardell was the next actor cast in the series, as the titular Mike.Swoosie Kurtz then joined the series as Molly's mother, Joyce. Following Kurtz, Nyambi Nyambi boarded the series as Samuel, a regular waiter at Abe's Hot Beef, where Mike and Carl frequent.Melissa McCarthy completed the cast when she signed on to play the role of the titular Molly.
The show has received moderately positive reviews from critics. It achieved a score of 63 out of 100 on the review aggregator site Metacritic, indicating "generally favorable reviews". Critic Randee Dawn gave the show a negative review, stating the cast is likable, but the jokes are old and bland.
There was a controversy in 2010 around a Marie Claire blog post written by Maura Kelly, in which she refers to the actors on the show as overweight. Show creator Mark Roberts spoke out regarding Kelly's blog post, calling the comments "very high school". He also stated, "This wasn’t about the show, this wasn’t about the writing, this wasn’t about the acting. This was about someone’s hateful response to how these two human beings look."Billy Gardell also addressed the matter when he appeared on the daily talk show The Talk on November 1, 2010.
Marie Claire has stood behind the blog. Kelly has since apologized regarding her comments, stating that she "sorely regret[s] that it upset people so much".
In the Season 3 episode "Molly's New Shoes", the Peggy character reacts to her fiancé's plans to retire and move to Arizona with the line: "Arizona? Why should I go to Arizona? It's nothing but a furnace full of drunk Indians." This prompted calls for an apology by the Native American Journalists Association, among others.
^Donovan, Bill (March 7, 2013). "Native leaders ask for apology for 'Mike and Molly' comment". Window Rock: Navajo Times. Retrieved March 9, 2013. Indian leaders have reacted negatively to a recent episode of the CBS comedy "Mike and Molly" that they said included racist statements. In the episode in question, Mike's mother, Peggy, who is played by Rondi Reed, reacted negatively to remarks that she should go to Arizona. 'Arizona? Why should I go to Arizona? It's nothing but a furnace full of drunk Indians,' the character says.