Chianti Classico is the heartland of the Chianti wine region – its traditional and longest-established viticultural area. The term classico is used in this way in several Italian wine regions (Orvieto and Valpolicella, for example), although Chianti is the most famous example. The typical Chianti Classico wine is a ruby-red, Sangiovese-based wine with aromas of violets and cherries and a hint of earthy spice.

Since the 1920s bottles of Chianti Classico wine have been marked by the DOCG's black cockerel (Gallo Nero) logo. However bottles sold in the US are not adorned with the bird, after a long running legal dispute begun by E&J Gallo Winery in 1991 was concluded in favour of the American company.

The symbol has a romanticised and much-told legend. In the 13th Century, the warring Tuscan provinces of Florence and Siena looked for a way to solve their ongoing border disputes. They agreed to a race; when the first cockerel crowed at dawn, each city would send out its fastest rider bound for the rival city. Where the two riders met would mark the new provincial boundary. The Florentines gained a head start by starving their (black) cockerel to make him sing earlier than the well-fed counterpart from Siena, so the two riders met only around 10 kilometres (six miles) north of Siena.

The modern-day Chianti Classico viticultural area now covers almost all land between Siena and Florence, buffered at each end by the Colli Fiorentini and Colli Senesi production zones. Of these and the other demarcated Chianti zones – Colli Aretini, Colline Pisane, Montalbano, Montespertoli and Rufina – the latter is the only one generally considered to rival the quality of Classico vineyards.

The very first classico area here was marked out in 1716 by Grand Duke Cosimo III de Medici. This was enlarged significantly in 1932, a change criticized as being over-generous and potentially damaging to the Chianti Classico name, and certainly varied in terms of terroir. Nevertheless, this larger area became legally recognized in 1966 when Italy began formalizing its wine laws and DOC system. In the 1980s, Chianti Classico was promoted from DOC to DOCG status.

Chianti Classico wines must contain a minimum of 80 percent of the Sangiovese variety. The remainder can be made from native grapes such as Canaiolo or Colorino, plus international varieties such as Cabernet Sauvignon and Merlot. Wines made only from Sangiovese have been permitted since 1996. The use of white grape varieties such as Malvasia and Trebbiano was prohibited 10 years later.

There are three quality levels within Chianti Classico wines: Annata (the standard wines) Riserva and Gran Selezione. Riserva wines must be aged for 24 months before commercial release. A Chianti Classico Gran Selezione must be made from a single estate and have been aged for a full 30 months. Since the category was introduced in 2013, it has also caused plenty of controversy, with some producers seeing it as unnecessary bureaucratic tinkering, pointing to a confusion between emphasis on terroir on one hand and the implication of human agency of the term selezione. Because the wines must be single estate products – not necessarily single vineyard wines – some very high production wines qualify; 500,000 bottles of Ruffino's Ducale d'Oro are made each year. On the other hand it is unlikely that the hundreds of Chianti Classico producers would be able to agree on classifying vineyards in the region in the manner of Chablis or the Côte d'Or.

The area's fame is due not just to the high quality of the wines, but also to the Classico zone's gastronomy and the iconic Tuscan landscape. The rural buildings and farmhouses are coveted by tourists and foreign residents. Agritourism and wine tasting tours are an important part of the region's wine economy and international profile.