The 35-year-old has apparently been keeping it in his back pocket until he's ready to pop the question and officially commit to 22-year-old Hough.
"He's had it for awhile and is in the process of planning the engagement. It's going to happen within the next few months or so!" the source said.
While they did not publicly confirm they were dating until November, Seacrest and Hough have been linked since last summer.
"Oh my gosh, he's phenomenal," Hough said during a November appearance on The Ellen DeGeneres Show. "He's really romantic -- He's not even in town, and I got in my car and there are flowers everywhere... just super sweet."
Last month, Seacrest denied rumors that the couple had already gotten engaged.
"I will give you breaking news," Seacrest said during an appearance on Good Morning America just before the New Year. "The breaking news is that I'm not. I'm not engaged," but he added, "I'm very happy."
According to another RadarOnline source, the American Idol host is truly head over heels for Hough.
"I don't think I've ever seen him like this over a girl before, ever... they fit together so perfectly," the source explained despite wanting to keep Seacrest's proposal plans secret.
"If Ryan was planning to propose, why would I spoil the whole surprise for him?" the source said.
In addition, the Idol host reportedly isn't the only Seacrest taken with Hough.
"All his family adore her too, and I know his mom would be really happy to see him settle down with Julianne and work on giving her some grandchildren!" the source noted.
And the feeling is mutual with Hough's family, according to her brother and fellow Dancing with the Stars pro Derek Hough.
"He just fits right in with the family," he told People in October.
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