Robert Morris was born to Robert Morris, Sr. and Elizabeth Murphet in Liverpool, Lancashire, England, on January 20, 1734.

At the age of thirteen, Morris had immigrated to Oxford, Maryland, to live with his father, who was a tobacco factor.

As a youth, Morris was provided a tutor and was a quick learner.

His father sent him to Philadelphia to study where he stayed with Charles Greenway, a family friend.
Greenway arranged for young Robert to become an apprentice at the shipping and banking firm of the Philadelphia merchant (and then mayor) Charles Willing.

A year later, Robert's father died after being wounded in an accident when hit by the wadding of a ship's gun that was fired in his honor.

When Charles Willing died in 1754, his son Thomas Willing made Morris his partner at the age twenty-four.

They established the prominent shipping-banking firm of Willing, Morris & Co. on May 1, 1757.

Their partnership is a merchant firm with interests in shipping, real estate, and other lines of business.

The partnership had been forged just after the Seven Years' War began (1754–1763), which had hindered attracting the usual supply of new indentured servants to the colony.

Potential immigrants are conscripted in England to fight in Europe, and the contracts for those already in the colonies in America are expiring.

Indentured servants can legally break their contracts to join the British forces to fight against the French and their native allies.

At the same time, the British Crown had wanted to encourage the slave trade which was profitable for the King's political allies in the African Company of Merchants.

While Morris was a junior partner and Willing was pursuing a political career, the company Willing, Morris & Co. had co-signed a petition calling for the repeal of Pennsylvania's tariff on imported slaves. (About two hundred slaves had been imported into Philadelphia in 1762, the height of the trade; most of whom were brought in by the Rhode Islanders Aaron Lopez and Jacob Rivera.)

Willing, Morris & Co had funded its own slave-trading voyage.

The ship had not carried enough to be profitable and, during a second trip, had been captured by French privateers.

The firm had handled two slave auctions for other importers, offering a total of twenty-three slaves.

In 1762 the firm had advertised an agency sale in Wilmington, Delaware for over one hundred Gold Coast slaves.

The ship had docked in Wilmington to avoid the tariff.

In 1765 on their last reported agency deal (out of a total of eight), the firm advertises seventy slaves who are brought in from Africa on the ship Marquis de Granby.

The slaves are not sold in Philadelphia, as the owner takes the ship and all the slaves to Jamaica.