Yes! Doing it that way is my #1 tip I learned from renovating our full bath.
Here's a link below to a lot of discussion of how I did it and how I was able to add vanity feet inexpensively.
I ran into the issue that the vanity ordering took the longest out of everything in our remodel. I preferred ordering from a cabinet salesperson to ordering a vanity online. Getting it ordered from a cabinet company (anyone who sells kitchen cabinets) was time consuming but that's how you can get what you want. It isn't custom but it does have to be ordered.
Going to a kitchen & bath store is the way I got my vanity that's exactly the size, color and combo that I wanted but couldn't find online. My experience was they take 6-8 weeks from your order date until then vanity cabinet arrives. In my small 24 inch size it was less expensive than many that I saw online. Here's a cabinet line you could try to find locally (by doing Contact Us at their site). Mine was Executive Kitchens. You can search it and view their bathroom photo gallery at bottom of their galleries page. Mine is burgundy finish on maple with shaker doors. Plus it's from their Green Kitchens line and is grown from sustainable forest wood and has a zero Volatile Compound finish (zero VOC).

Here is a link that might be useful: Post about vanitiy ordering from kitchen cabinet company

I have heard posts here complaining about Martha Stewart's line. Have you considered Restoration Hardware or Pottery Barn? Anything ordered from a company making vanities does take at least 6 weeks and you have to hope they get it right or it will be another 6 weeks. Its also somewhat difficult and generally more expensive to have it made by a carpenter unless you know just the right person. Some or many plumbing supply stores will sell floor models at certain times. Also everyone raves about faucetdirect.com so maybe you could check them out.

I was worried about that. The MS line is beautiful though. I ordered my vanities from Restoration Hardware for our beach house and while they are stunning and great quality the actual process was a nightmare! Had to reorder vanity twice and the counter came 4 times before I got one not cracked!
Thanks, I will looking into faucetdirect :)

We considered using a kitchen cabinet for the bathroom, however, the kitchen cabinets were 24" deep compared to 21" and I didn't want/need more depth.

Would anyone visiting here not recommend Restoration Hardware for a pedestal sink(no vanity involved)?

We used a kitchen cabinet for our bathroom remodel, and will do it again as we wanted the taller height. The company (Omega/Dynasty) just made it skinner so it was only 21 inches deep. We just started another bath renovation, and will do the same thing again. I think most of the companies that make kitchen cabinets can make one you can use in the bathroom (at a variety of heights and widths).

I did this with IKEA cabinets. Just took 3 inches off the back of the boxes - I think as long as they're at least 21 inches deep the regular size drawers still fit. It looked completely built in but was pretty inexpensive. I think it was a 24" middle cabinet (where the sink was) and 2 18" 4-drawer cabs on either side. I loved it.

I'm positive that Diamond and Kraftmaid make cabs for vanity sizes in addition to kitchen sizes. I thought that most major semi-custom cab lines did this. Check out those two companies websites, or stop by Lowes or HD to look in their cab depts. They all sell white cabs.

Depending on the size of your vanity, you might need to have a cab installer or carpenter/handy person install.

i wanted a built in cabinet linen closet in the bathroom... but didn't like the options available in the bathroom cabinets (i wanted them to be extra tall, with drawers and shelves above and below the drawers) so we used 'pantry' kitchen cabinets-24" depth which is actually an awesome depth to have for linens, hamper, etc...