Wiseman confirmed on Twitter that the 'Take A Chance On Me' star popped the question during a romantic holiday to Antigua.
"Its official Marvin proposed 2me 2day,wanted 2 tell u b4 some1 else did!" she wrote. "SO excited 2 b Mrs Humes.x (sic)."
Wiseman also posted a picture of the couple sharing a glass of champagne on a beach with her engagement ring clearly on display.
Humes made a similar announcement on the official JLS Twitter account: "Happy New Year everyone!!! So everyone hears it from me..Rochelle and I are engaged!! Party time tonight! Have a great one..All love..Marv x"
Following the couple's respective revelations, the topic 'Marvin and Rochelle' and the hashtag '#CongratulationsMarvelle' began trending on the social networking site.
Watch The Saturdays in the video for 'My Heart Takes Over' below:
Una Healy was the first of Wiseman's Saturdays colleagues to comment on the 22-year-old's engagement, tweeting: "Congratulations to our gorgeous @RochelleTheSats and her lovely Marvin @JLSOfficial on their engagement, so happy for them :-) ."
Oritsé Williams of JLS also applauded the couple, declaring: "First JLS marriage!! Gwaaann Marv and Roch!! Thats #MarriedSwag..Congrats!!!"
Bandmate JB Gill added: "Woooooooo!wedding time!!2012 is going INNNN already!congrats marv and @RochelleTheSats :D HAPPY NEW YEAR EVERYBODY!!!"
With congratulatory messages flooding in from their fans, Humes later gushed on Twitter: "Thank you so much for all the love.We are the happiest 2 people in the world.A perfect start to 2012.This year is gonna be massive.Luv ya."
The pair began dating in February 2010, briefly split the following November and reconciled early this year.
Humes had been tipped to propose over the festive season after giving Wiseman a promise ring in September.
Watch JLS in the video for 'Take A Chance On Me' below: