The Hunter Valley is unquestionably the best-known and most highly prized wine region in New South Wales. The area is of significant historical importance to the Australian wine industry, which effectively started there. It was home to James Busby, the 'godfather' of viticulture in both Australia and New Zealand. Busby's pre-phylloxera European vine cuttings, which he shipped over from Europe in the 1830s, were the ancestors of some of Australia's oldest living vines. The valley's winemakers have pioneered two distinctive styles of wine (oaked Chardonnay and dry, varietal Semillon) and has retained a strong connection with both of them.

The Hunter Valley's most famous wine style is its distinctive dry Semillon, made there since the 1870s. Hunter Valley Semillons are renowned for their ability to improve with age; the better examples develop in bottle for more than 15 years. The wines start out with a fresh, grassy, citrus taste and evolve into golden wines with nutty, honeyed notes and a luscious mouthfeel. The valley's relationship with Chardonnay is 100 years shorter, but no less significant. It was here that Australia's first Chardonnay was made, from vines planted by the Tyrrell winery of Pokolbin in 1968. Tyrrell's maintains a strong presence in the region today. The style caught on rapidly, and spread all across Australia throughout the 1970s and 80s, gaining immense, lasting popularity.

Australia's national red grape, Shiraz, is also long-established in the Hunter Valley. Like the other wine styles from the region, it has a character which is as much regional as it is varietal – equal parts 'Hunter' and 'Shiraz'. Tasting notes often mention notes of earthy leather and tar. Like their Semillon counterparts, the better examples of Hunter Shiraz age gracefully over two decades or so.

With its low latitude (32/33°S) and relatively wet climate, the Hunter Valley is not an obvious candidate as a source of quality white wines. It is not delicate finesse which has earned the wines their solid reputation (very few Hunter Valley wines which could be described as delicate), but their distinctive style and ageing potential which have earned them. The key to the style, and the region's viticultural success, is the local mesoclimate, cooled by regular afternoon cloud cover and gentle breezes which reach inland from the coast. Together, these two climatic factors temper the otherwise prohibitively high temperatures, and allow the vines some respite from the baking Australian sun.

A slight complication in the valley's wine administration is that 'Hunter Valley' GI (Geographical Indication) is distinct from the slightly smaller 'Hunter' GI, even though they cover roughly the same geographical area. The technical difference between the two is very subtle. The 'Hunter' GI was created in 1997 to increase the focus of the wider Hunter brand. It refers to a more exclusive area of the wider Hunter Valley, omitting national parks, the Newcastle metropolitan area, and land immediately along the coastline. Most significantly, it also excludes any land within the shire of Mudgee, which is reserved for the Mudgee GI. It is within this smaller Hunter area that three other local GIs (Upper Hunter Valley, Broke Fordwich and Pokolbin) are located.

The Hunter Valley has long been (unofficially) divided into lower and upper sections, despite these being very similar in terms of both climate and topography. In July 2010 this division became official, with the advent of the Upper Hunter Valley GI. At the same time, the Pokolbin GI was created, to cover the vineyards along the lower reaches of the Hunter River, just west of Newcastle. Broke Fordwich is a smaller, much longer-established sub-regional GI, a neat L-shaped area of red volcanic soils around the towns of Broke and Fordwich.