He was the third child of Franciszek Strzelecki and Anna née Raczyńska, both from Polish nobility (szlachta), who leased the Głuszyna estate at the time.

He eventually came under the notice of the Polish Prince Franciszek Sapieha who placed him in charge of his large estate in the Russian-occupied part of Poland.

Eustace refused to pay Strzelecki the prince's bequest – a huge sum of money and a considerable estate – accusing him of bad faith and prevarication.

[10] He wrote: "I had gone with my host to look at the farm, the fields, and the vineyard, — contiguous to which last stood in a row six neat cottages, surrounded with kitchen gardens, and inhabited by six families of German vine-dressers, who emigrated two years ago to New South Wales, either driven there by necessity, or seduced by the hope of finding, beyond the sea, fortune, peace, and happiness, – perhaps justice and liberty.

In September he discovered gold and silver near Wellington (NSW) and in the Vale of Clwyd,[citation needed] in the vicinity of Hartley.

After passing the La Trobe River it was found necessary to abandon the horses and all the specimens that had been collected and try to reach Western Port.

For 22 days they were on the edge of starvation and were ultimately saved by the knowledge and hunting ability of their guide Charlie, who caught native animals for them to eat.

From 1840 to 1842, based in Launceston, Tasmania (then known as Van Diemen's Land), Strzelecki explored nearly every part of the island, usually on foot with three men and two pack horses.

His friends, the Lieutenant-Governor, Sir John Franklin, and his wife, Lady Jane,[15] afforded him every help in his scientific endeavours.

The book gained the praise of Charles Darwin and other scientists and was awarded the Founder's Medal of the Royal Geographical Society.

In it, he describes terra nullius as a "sophistry of law" and writes that Aboriginal Australians are "as strongly attached to... property, and the rights which it involves, as any European political body.

He extended daily food rations to schoolchildren across the most famine-stricken western part of Ireland, while also distributing clothing and promoting basic hygiene.

Despite suffering from the effects of typhoid fever he contracted in Ireland, Strzelecki dedicated himself tirelessly to hunger relief.

He was, for many years, an active member of Family Colonisation Loan Society, originated by Caroline Chisholm and in 1854 was its chairman, fulfilling his duties with great zeal.

Strzelecki was made a fellow of the Royal Geographical Society and was awarded its Founder's Medal for "exploration in the south eastern portion of Australia".

[20] In 2023, the city of Poznań declared 2023 as "The Year of Strzelecki" in order to honour and celebrate the life of the explorer and his accomplishments.