A rep for the blonde beauty confirmed the happy news on Thursday evening (21 November) but there's no word yet on where the proposal took place or whether any wedding plans are in motion.
Whitney, 28, met Tim when he was an associate producer on her MTV series The City, a spinoff from The Hills, where she first rose to fame.
They didn't start dating until a few years after The City ended and despite meeting on a reality show set, have kept their romance out of the limelight.
Whitney's engagement comes hot on the heels of her former co-star Lauren Conrad, who accepted a proposal from her boyfriend William Tell in October.
Another Hills star, Holly Montag, also became engaged in October.
Congrats to Whitney and Tim!
More engaged celebrities in our gallery below!
Copyright: Instagram Mark Wright
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