The news was announced on-air during Tuesday's episode of the popular CBS daytime talk show. Osmond will join fellow hosts Eve, Carrie Ann Inaba, Sharon Osbourne and Sheryl Underwood on the show, after Sara Gilbert announced in April that she was leaving after nine years in order to spend more time with her kids and focus on other projects.
Osmond, 59, will start her new gig in September.
"It is such a joy for me to be joining The Talk in September," she said in a statement. "After guest co-hosting and appearing as a guest on the show throughout the years, I am thrilled to now call this my day job. I look forward to working with Sharon, Sheryl, Eve and Carrie Ann, who are such smart, strong, talented women whom I immensely respect. I cannot wait to share this exciting new chapter with the viewers and the CBS family."
Angelica McDaniel, Executive Vice President, Daytime Programs, and Syndicated Programs Development, CBS Entertainment and CBS Television Distribution, also said in a statement, "If you've seen Marie Osmond guest host on The Talk over the past nine seasons, you know she's the perfect addition to the show. Marie's impressive career accomplishments have endeared her to fans throughout the decades. Her willingness to be authentic and share personal triumphs and struggles with honesty in the hopes of helping others always resonates. I'm excited to kick off season 10 with the multitalented, dynamic Marie at The Talk table."
On Tuesday's show, Osmond, clad in a red suit, individually praised each host, and said that getting to work with the women is a "dream come true."
"I have so much gratitude in my heart today," she said. "I am honored to be here. I am so excited to be here."
"I always wanted sisters," she later quipped, referring to her eight brothers.
Osmond's new gig will overlap for about two months with her residency at the Flamingo hotel in Las Vegas with her brother, Donny, which ends on Nov. 16.
ET spoke to both Osmond and her brother in March, and Donny actually addressed the possibility of working in daytime TV again. The two had a talk show, Donny & Marie, which aired from 1997-2000.
"Yeah, well, you know, we're open for anything at this point," he said. "We do want to fulfill our own little projects that we've got going."
Osmond also said she had lots of projects on her plate, and time was of the essence.
"I have some things right now that I'm excited about," she said. "I have a movie that I'm working on in August, and another one after that, and some television things, and so yeah, time and it's time sensitive. You can't do those things, you know ... I may be that little old lady who on Broadway that comes out and does the funny role but right now .... I've got an album that I'm working on and it's time sensitive, while your voices are still in shape and you're doing things."