The rebrand spans a new brand identity, mail-order catalogue and e-commerce site.
The will later this month be given a new look featuring multiple homepage layouts, a tabbed product carousel, videos, reviews, blogs and forums.
About 700,000 copies of Long Tall Sally's 84-page catalogue, featuring a fresh layout, will be distributed in the UK, with a trial in the US.
The new catalogue and website are part of a drive by Long Tall Sally to expand its direct shopping business overseas.
Paul Lewis Design was appointed to work for the retailer in March 2008, after winning a five-way pitch.
Andrew Shapin, managing director of Long Tall Sally, said: "Paul Lewis Design clearly understood what was required to take the Long Tall Sally brand forward and make it the first choice in fashion for tall women.
"The strength of its vision and concepts has meant that we've achieved this and more."