According to the magazine, the 42-year-old actress, who has dated Justin Timberlake and Alex Rodriguez in the past, and the Good Charlotte rocker have decided to tie the knot after dating for only seven months.
The couple were first spotted in May of this year and despite their relatively short courtship, they are ready to make it official.
"Everyone thinks it's wild but are so happy for them," a source told Us. "Benji always tends to fall in love easily, but this time it's for real and he landed a great girl. They obviously both make each other incredibly happy and there's nothing better than that."
— Us Weekly (@usweekly) December 19, 2014
According to a source for the The National Enquirer, as reported by RadarOnline, they’re “planning their wedding for early in the new year. They’ve been telling close friends in recent weeks about their plans, but it’s very hush-hush.”
In September, a friend of the couple told Us that Madden really wanted to do things right when it came to his relationship with Diaz.
"He is more traditional then her," the pal said. "She really doesn't care about getting married but wants babies. He wants to get engaged and married first."
— ELLE Magazine (US) (@ELLEmagazine) December 19, 2014
"I approve of anything that's going to make Benj happy," she told Watch What Happens Live's Andy Cohen back in July. When asked if she set them up, she answered, "Yes, I'm going to take responsibility for everything!"
However, Radar reports that Joel is not necessarily keen on the union and has been trying to get them to cool their jets.
“It’s way too soon to be discussing marriage, and Joel told him so,” the source told the website. “He’s told him to slow down and enjoy the dating phase.”