A specific date is not known but historical documents and profiles by institutions such as The Royal Mint, record that Jean Baptiste Merlen was born in 1769.

Not much is known about his early life but it is thought Jean Baptiste Merlen grew up in Brussels, continuing to study up until his early twenties under master craftsmen, learning the highly specialised art of die-sinking, punch-cutting, and medal design.

The earliest known work of Jean Baptiste Merlen is the 'Jetons de Présence', attendance tokens or prize medals that were commissioned for local academic institutions. A prominent bronze prize medal created by Jean Baptiste Merlen for the 'Société de Médecine de Bruxelles', or the Medical Society of Brussels, was released around 1804.

His exceptional execution of these early regional commissions in Belgium caught the attention of French numismatic authorities, paving the way for his move to The Paris Mint later that same year, during the Napoleonic era.

In the late 18th century or by the very early 1800's, Jean Baptiste Merlen moved to Paris, eventually being formally employed by The Paris Mint in 1804.

The first project for Jean Baptiste Merlen and his most famous was the commemorative medal for Napoleon Bonaparte. The 'Proclamation and Coronation of Bonaparte as Emperor', medal, was created under the direction of 'Baron Dominique Vivant Denon', at The Paris Mint in 1804. The medal was created to commemorate the coronation of Napoleon Bonaparte as 'Napoleon I', and 'Emperor of the French', which took place at Notre Dame Cathedral in Paris on 2nd December 1804.

Jean Baptiste Merlen spent much of his time at The Paris Mint documenting each military victory and civic achievement of Napoleon Bonaparte, with the design and release of a large series of medals. His role at The Paris Mint involved creating the precision fonts and borders required to standardise the look of imperial medals, while designing the allegorical laurels, shields and imperial eagles which featured on the military medals.

One of his final pieces for The Paris Mint was the engraving of a medal which celebrated the return of Napoleon Bonaparte to France in March 1815. Returning to France after escaping exile from the Island of Elba, the period, known as the 'Hundred Days', refers to Napoleon Bonaparte briefly reclaimed power in France. However, after the final defeat at the Battle of Waterloo in 1815, The Paris Mint was left in chaos, prompting Jean Baptiste Merlen to move, taking his skills to London.

The law didn't allow for foreign nationals from holding permanent, official positions at The Royal Mint. Because of this, when Jean Baptiste Merlen arrived at The Royal Mint in 1820, the Master of the Mint, William Wellesley Pole, desperate to use him for his mastery of steel engraving, hired him as an 'Extra Assistant Engraver', a unique, unofficial position.

Entering into a tense, highly competitive workspace at that time, The Royal Mint was in the process of overhauling the national currency following 'The Great Recoinage', while two of it's key artists, William Wyon and Benedetto Pistrucci were in constant conflict with one another.

Jean Baptiste Merlen was initially given control over the designs which were used on the reverse or 'Tails', side of the coins being minted at The Royal Mint. Meanwhile, Benedetto Pistrucci and William Wyon fought over who would engrave the King's portrait on the obverse.

In his first year, Jean Baptiste Merlen designed the reverse of the 1820 George IV Half Crown Coin, which featured a crowned shield that was surrounded by the national floral emblems of the United Kingdom.

In 1821, Jean Baptiste Merlen was asked to create the portrait of King George IV that was based on a bust sculpted by Sir Francis Chantrey, after Benedetto Pistrucci refused to copy the work of another artist to create the portrait. Between 1821 and 1823, Jean Baptiste Merlen designed and created the famous 'Bare Head', portrait of King George IV that first appeared on the 1823 Double Sovereign, making history as the first time a male British monarch was depicted on a coin without a crown or laurel wreath.

In the same period, Jean Baptiste Merlen was also tasked In 1822 with completely redesigning the silver coins being used for the monarch's historic Maundy Money. Introducing an elegant design, Jean Baptiste Merlen created Maundy Money that featured the numerical value of the coin, nestled inside an intricate oak wreath topped with a royal crown, a design which has been largely unchanged that continues to be used today.

By this point, Benedetto Pistrucci had essentially gone on strike with The Royal Mint essentially stripping him of his control over the Sovereign coin, with his famous 'St. George & Dragon', design for the Sovereign coin being dropped entirely. While the task of creating the new 'Bare Head', portrait of King George IV being given to Benedetto Pistrucci’s rival, William Wyon, the task of a new design for the reverse of the Sovereign coin was given to Jean Baptiste Merlen.

Highly respected for his technical skill with heraldic imagery, Jean Baptiste Merlen created an intricate, garnished 'Shield of the Royal Arms of the United Kingdom', design to replace the St. George and the dragon design. The design which Jean Baptiste Merlen created included a crowned Royal Shield of Arms that featured the Passant Guardant Lions of England, a floral bordered Lion Rampant of Scotland and the Harp of Ireland, with a smaller crowned shield, known as the 'Central Escutcheon', in the centre.

During his time at The Royal Mint, Jean Baptiste Merlen also played a crucial role in the background operations at The Royal Mint. Highly valued for his expertise in production and tooling, Jean Baptiste Merlen created the precise lettering punches, borders and date dies used to strike uniform, high quality coins across almost all of the active denominations being produced at The Royal Mint.

Jean Baptiste Merlen left The Royal Mint in July 1844 after a successful tenure which lasted 24 years, officially retiring at the age of 75. After his retirement, the responsibilities of the engraving department passed to the Chief Engraver William Wyon with his son, Leonard Charles Wyon, entering The Royal Mint to pick up duties of Jean Baptiste Merlen.