Novosielski was born into a Polish family in Rome in 1750. He moved to London as a young man and worked on a number of architectural projects. In 1782, while working as a scene-painter, he managed to talk his way into getting the job to refurbish the King’s Theatre in Haymarket. When it burnt down in 1790, he was the architect appointed to rebuild it.
Novosielski was one of the first people to see the potential of the agricultural land of Kensington as overspill for London’s burgeoning residential population. He was following the lead of Henry Holland who had built Hans Town in Chelsea in the 1770s.
In the late 18th century, the Kensington Estate of Henry Smith's Charity was mainly agricultural land devoted to nurseries. In 1759 the trustees had granted a lease of most of the land to Samuel Bucknall for a term of seventy years. In 1785 Novosielski persuaded his successors to grant him an underlease of fourteen acres.
The underlease was for forty-five years, which was what remained under the Bucknall lease. It granted Novosielski the right to build houses, and in return. Novosielski had to pay a rent of £140 a year (but a reduced amount for the first five years to give him time to complete the development and let the houses first).
Novosielski planned a terrace of houses along Brompton Road with a square behind. The terrace was completed by about 1795 and contained forty-four houses. Novosielski called it Michael’s Place in honour of himself. The houses were four storeys high and sold for £350 to £450 each. William Cobbett lived at No. 11 in 1820. In the middle, the terrace was divided by a new road which Novosielski called Michael’s Grove (and which is now Egerton Terrace). At the south end of Yeoman’s Row, Novosielski built himself a very grand mansion called Brompton Grange. He also started work on a crescent of houses called Novosielski Street, opposite Egerton Crescent, but the name was changed to Brompton Crescent after his death.
When he died in 1795 the London property boom which had sustained him had come to an end. He left many of his projects uncompleted. His widow had to sell Brompton Grange and move to 13 Michael’s Place. His underlease was taken by Ransom, Morland and Hammersley’s bank, who had been financing his developments.
In due course, Novosielski's underlease ended and the properties all reverted to the Smith’s Charity trustees. They then rented the houses out at full market rent. In fact it was rent from these houses which provided the Charity with most of its income in the 19th century. The transformation of the estate from nurseries to houses did not greatly affect the Charity's finances until the builders' leases came to an end. Until then the Charity was only receiving ground rents.
Not one of Novosielski's Kensington houses has survived. Brompton Grange was demolished by the Smith’s Charity trustees in 1843 and replaced by Egerton Crescent, Crescent Place and Egerton Terrace.

