The stock recently was rising $15.61, or 14.5%, to $12.38.
For the first quarter ended Nov. 17, the Memphis, Tenn., company earned $132.5 million, up 7% from $123.9 million a year earlier.
On a per-share basis, earnings jumped 17% to $2.02 from $1.73 last year, as the average number of shares outstanding dropped 9% due to buybacks. Analysts polled by Thomson Financial expected earnings of $1.91 a share.
Sales rose to $1.46 billion from $1.39 billion a year earlier, exceeding Wall Street's forecast of $1.44 billion.
Same-store sales, or sales at stores open at least a year, increased 1.3%.
Gross margin also improved, rising to 49.9% from 49.2% the prior year. AutoZone attributed the rise to better merchandise management, as well as a shift in sales toward higher-margin products.
Shares of AutoZone, like those of most retailers, have slid in recent months as investors fear a consumer slowdown. The stock traded at a 52-week high of $140.29 in July, but had fallen to a 52-week low of $103.40 last week.