After his father's death, Cabot conducted his own voyages of discovery, seeking the Northwest Passage through North America on behalf of England.

He later sailed for Spain, traveling to South America, where he explored the Rio de la Plata and established two new forts.

[1] Late in life, Cabot himself told Englishman Richard Eden that he was born in Bristol, and that he travelled back to Venice with his parents at four years of age, returning again with his father, so that he was thought to be Venetian.

[4] John Cabot sailed from Bristol on the small ship Matthew and reached the coast of a "New Found Land" on 24 June 1497.

He is generally credited with gaining "the high latitudes", where he told of encountering fields of icebergs and reported an open passage of water, but was forced to turn back.

This would imply that he reached as far as the Chesapeake Bay, near what is now Washington, D.C.[10] Returning home "he found the King dead, and his son cared little for such an enterprise".

The scholar and translator/civil servant Richard Eden, who came to know Cabot towards the end of his life, ascribed to the explorer 'the governance' of a voyage of c.1516 under English flag.

He had the support of Henry VIII and Cardinal Wolsey, and some offers of backing in money and ships from both Bristol and London merchants.

[17] Believing that King Ferdinand II of Aragon was giving more financial support to exploration than the English, Cabot moved to Spain from England in 1512.

By 1522, he was once again working for Spain as a member of the Council of the Indies and holding the title of Pilot Major,[19] where he supervised naval and navigator training, etc.

On 4 March 1525, he was given command of a fleet that was to determine from astronomical observation the precise demarcation of the Treaty of Tordesillas, which defined the area of Spanish and Portuguese monopolies.

When Cabot landed with his expedition in Brazil, however, he heard of the rumours of the great wealth of the Incan king and the nearly-successful invasion of Aleixo Garcia.

He abandoned his charge and explored the interior of the Río de la Plata along the northern border of present-day Argentina.

Cabot had already earned the disapproval of his crew by stranding the fleet in the doldrums and running the flagship aground off Santa Catarina Island.

Purchasing 50 slaves there, he traveled along the coast of Brazil before heading across the Atlantic, reaching Seville on 22 July 1530, with one ship and 24 men.

In the year 1553, Cabot discussed a voyage to China and re-joining the service of Charles V with Jean Scheyfve, the king's ambassador in England.

He became governor of the Muscovy Company in 1553 and, along with John Dee,[23] helped it prepare for an expedition led by Sir Hugh Willoughby and Richard Chancellor.

[26] On June 22, 1523, Sebastian Cabot, acting as Catalina Barba y Medrano's guardian, appointed Fernando de Jerez as her attorney and arranged her property schedule.

[27] In November 1523, a Real Cédula confirmed Catalina Barba y Medrano’s legitimacy and marriage, ending legal disputes.

Despite financial challenges, Catalina de Medrano's dowry (267 ducats) and business expertise supported Cabot, who granted her power of attorney in June 1524—a rare move for the time.

Catalina de Medrano managed family finances, settling debts and handling business affairs, though she faced challenges like gender-related reluctance in transactions.

Her family had long-standing connections with Spanish nobility, supplying fine cloth and goods to the royal court in the late 15th century.

[27] Catalina de Medrano exemplified the resilience of Seville’s women, who often managed families and businesses during uncertain times.

Her second marriage to Cabot, based on trust and respect, secured her daughter’s inheritance and maintained her vital role in navigating the complex social and financial challenges of the period.

[28] The result was that the influential geographical writer Richard Hakluyt represented his father John Cabot as a figurehead for the expeditions and suggested that Sebastian actually led them.

When new archival finds in the nineteenth century demonstrated that this was not the case, Sebastian was denigrated, disparaged by Henry Harrisse, in particular, as a man who willfully appropriated his father's achievements and represented them as his own.