The pair have been dating since July 2013, and Jenny bought Donnie on to her television show The View to announce the news.
"I just got engaged!" Jenny said live on air, before revealing her hidden hand which had been kept behind the desk.
Jenny McCarthy and Donnie Wahlberg on New Years Eve 2013
The 41-year-old then proceeded to jump around the set and invited Donnie, who was backstage, out on to the set.
When asked about the ring, Jenny explained: "It's a yellow sapphire."
Both Jenny and Donnie were in tears after revealing the news.
Jenny added that her son Evan, who is her son from her first marriage, was involved in the proposal.
Celebrities with yellow engagement rings
Jenny told her co-hosts and the audience: "This weekend I was sitting with Donnie and he went into the other room and out came Evan with a card that said 'Will.' And he ran away and came back with a card that said 'You,' and I knew what was happening and I just started crying. And then he came out with a card that said 'Marry,' but it was spelled 'Mary,' and the last time Donnie came out with Evan and Evan's shirt said 'Me?' and he was holding the ring. He asked, 'Will you marry me?' I of course said yes. And in that moment, Evan yelled, 'I have another dad! I have another dad.' And it was just, it made all of us cry."
She added: "I feel like the luckiest girl in the world. He's so wonderful."
Earlier this morning Jenny teased fans with a big announcement, tweeting: "Good morning my friends. Have a kick ass Wednesday. Between us... I would watch
Good morning my friends. Have a kick ass Wednesday. Between us... I would watch #theview today. Just Sayn. Xxoo— Jenny McCarthy (@JennyMcCarthy) April 16, 2014
Turn on #theview It's gonna be a goooood one. : )— Jenny McCarthy (@JennyMcCarthy) April 16, 2014
Donnie, 44, then tweeted “#Happy” to his nearly 600,000 Twitter followers.
When asked about the wedding date by her co-host Barbara Walters Jenny told her she didn’t know, but that August was a consideration.
This is the second marriage for Donnie as well, who has two sons from his previous nine-year-marriage. The former Playboy model was previously in a four-year relationship with actor Jim Carey.
Donnie, who used to be a member of the 1980s boyband New Kids on the Block, is now an actor and radio DJ.
Dropping by @theviewtv to visit my girl...— Donnie Wahlberg (@DonnieWahlberg) April 16, 2014
Jenny had previously revealed that their work ethic was what made them connect.
Speaking to People magazine, Jenny said: "He understands my work schedule and he has his and I get it. And we're both single parents and he's trying to juggle all of that while I am too."