The 27-year-old former reality TV star is ''beyond thrilled'' after the 33-year-old rocker turned law student proposed to her over the weekend.
The former 'The Hills' star wrote on her blog on Sunday (13.10.13): ''I am very excited to share with you guys that William and I got engaged over the weekend. I am beyond thrilled! Get ready for lots more wedding content here on LaurenConrad.com as we begin the planning process.''
The blonde beauty also shared a picture of her classic diamond engagement ring, and later added: ''William and I are overwhelmed by all of your warm wishes. Thank you so much for sharing in this special moment.''
Lauren recently revealed she and William, who have been together for 21 months, are perfect for each other because they have so much in common.
She said: '''He is very good for me because we have a lot in common as far as where we grew up. It's the first time I'm with someone and I'm not explaining things.
''He also has experience in the entertainment industry, so he understands a lot of things that people don't always get.''
News of her engagement comes just one day after her ex-boyfriend and 'Laguna Beach' co-star Jason Wahler married his fiancee, Ashley Slack, in Malibu, California, on Saturday (12.10.13).
'Smalls Change (Meditations Upon Ageing)' arrives in April.
The two awards have made for a great 72nd birthday present for the country music icon.