The world's best sprinter Black Caviar has been immortalised on a postage stamp in commemoration of her 20th straight career victory, which came at Morphettville late last month.

Australia Post last week released a souvenir pack featuring all 20 of the champion mare's race wins, just four days before Peter Moody's England-bound five-year-old extended her unbeaten run to 21.

Black Caviar enjoyed perhaps her softest win yet on Saturday in the Group 1 Goodwood at Morphettville, cantering to the line for another emphatic, but relatively narrow triumph.

The stamp pack includes two 10 x 60c Southern Cross sheets depicting each of her 20 wins, plus an image of Black Caviar and jockey Luke Nolen in full stride.

A detailed list of all 20 wins, an Australasian record, is also attached.

“Australia Post is delighted to honour the 20th consecutive win of Black Caviar by producing a special souvenir stamp pack for this undefeated Australian champion,” Australia Post philatelic manager Michael Zsolt said.

“We wanted to create a great souvenir featuring one of Australia's true racing champions for everyone to collect.

“The souvenir stamp pack captures the excitement and achievement of this magnificent racehorse, and will resonate with horse-racing enthusiasts and collectors alike.”

The Black Caviar souvenir stamp pack is available for purchase at participating Australia Post retail outlets, via mail order on 1800 331 794, and online at auspost.com.au/stamps while stocks last.