Her 1663 manuscript Observations, on the materials and techniques employed "in her painting of Apricots", though not printed, is the earliest known instructional text in English written by a female painter.

Praised first as a "virtuous" practitioner in "Oyl Colours" by Sir William Sanderson in his 1658 book Graphice: Or The use of the Pen and Pensil; In the Excellent Art of PAINTING, Beale's work was later commended by court painter Sir Peter Lely and, soon after her death, by the author of "An Essay towards an English-School", his account of the most noteworthy artists of her generation.

A group of painters worked in Bury St Edmunds, including Peter Lely and Matthew Snelling, whom Mary may have met in her youth.

[7][a] Not much is known about her death besides that she died in a house on Pall Mall and was buried under the communion table of St James's Church, Piccadilly.

[citation needed] Peter Lely, who succeeded Anthony van Dyck as the court painter, took a great interest in Mary's progress as an artist, especially since she would practice painting by imitating some of his work.

[19] Mary Beale started working by painting favours for people she knew in exchange for small gifts or favors.

Charles wrote thirty notebooks' worth of observations over the years, calling Mary "my dearest heart".

[2] She received a humanist education from her father,[24] During her childhood in Suffolk Mary's father was friendly with contemporary British artists such as Sir Nathaniel Bacon, Robert Walker, and Sir Peter Lely, leading to both Robert Walker and Peter Lely being "the most likely drawing masters to the young Mary".

[24] The exact time of Mary's introduction to Lely is debated and one theory has the two meeting prior to her marriage to Charles, when she was living in Suffolk.

Her near-contemporary George Vertue (1684–1756) records that Lely's portraits of Mary and her family were present at their home at Hind Court in 1661.

The work was found in a notebook collecting writings by Charles Beale but was written entirely by Mary, which Helen Draper states is "a unique example of husband-and-wife collaboration in the history of technical literature on painting.

[26] Mary's father, an amateur artist, funded her general education may have including courses in painting and drawing.

[20] Some of these people included Queen Henrietta Maria and John Tillotson, a clergyman from St James' Church, a close friend of Mary Beale who eventually became the Archbishop of Canterbury.

It may be due to Mary's father, John, who was a rector, or her close connection to Tillotson that kept the clergymen of St James' as consistent customers.

Mary's connection to Tillotson as well as her strong Puritan marriage to Charles worked in her favour in building up her good reputation.

He became the 2nd Duke of Newcastle in 1676 and he and his Duchess Frances née Pierrepont were frequent patrons of Mary, from whom they commissioned their portraits in 1677.

William Pierrepont was supportive of Oliver Cromwell during the English Civil War and remained an opponent to the Restoration of the Stuart Monarchy.

Baroque art is a style of sculpture, painting, music, and architecture that was prominent in Europe from the early 17th century until the mid 18th.

Baroque art is characterized by use of light and shadow, depictions of movement, as well as use of rich colour, all to elicit a sense of grandeur and awe.

Beale was the subject of a solo exhibition in 1975, at the (then) 'Geffrye Museum' (since renamed as the 'Museum of the Home'), which transferred to the Towner Art Gallery in Eastbourne the following year.

More recently (summer 2024), her work was shown in the 'Fruits of Friendship' exhibition at the Philip Mould & Co gallery in Pall Mall,[38] the street where she lived and died.