Starting in 1755, he resided in Amsterdam where he occupied a chair of anatomy and surgery at the Athenaeum Illustre, later completed by a medicine chair. He investigated inguinal hernia, patella and the best form of shoe. He withdraw five years later to dedicate himself to scientific research and lived on a property just outside Franeker. In 1762 he became politically active, a year later he chose to accept the chair of anatomy, surgery and botanics at the University of Groningen. Camper started a surgical clinic and showed selfmade drawings to illustrate his eloquent lectures, before retiring in 1773. His attention was for zoology and his collection of minerals and fossils.

Among his many works, he studied osteology of birds and discovered the presence of air in the inner cavities of birds' skeletons. He interested himself to the anatomy of eight orangutans, demonstrating against contemporary theories that it was a different species from the human being, and not simply a "degenerate" type of human. Petrus Camper published memoirs on the hearing of fish, the sound of frogs, investigated an elephant, and a rhinoceros from Java. He studied the rinderpest, rabids.

He was visited by Samuel Thomas von Sömmering, who later became professor in Göttingen. He became an associate of the French Academy of Sciences and had a eulogy in his honour composed by Nicolas de Condorcet and Félix Vicq - d'Azyr. In 1776 he became involved in a plan of dike construction. In 1780 he took lessons from Étienne Maurice Falconet. In his ideas about art Camper was influenced by Johann Joachim Winckelmann. He made drawings of the Dolmen south of Groningen. He was in the selection committee for the new townhall in Groningen. He became one of the directors of the Admiralty of Friesland. He was appointed as an (Orangist) burgomaster of Workum in 1783, opposing the Patriots (faction). In September 1787 he became the president of the state council of the Dutch Republic and warmly welcomed the stattholder William V of Orange and his wife Wilhelmine of Prussia. At the end of life he suffered from pleuritis, Camper drank a good glass of champagne and died.

One of the first scholar to study comparative anatomy, Petrus Camper demonstrated the principle of correlation in all organisms by the mechanical exercise he called a "metamorphosis". In his 1778 lecture, "On the Points of Similarity between the Human Species, Quadrupeds, Birds, and Fish; with Rules for Drawing, founded on this Similarity," he metamorphosed a horse into a human being, thus showing the similarity between all vertebrates. Étienne Geoffroy Saint - Hilaire (1772 – 1884) theorized this in 1795 as the "unity of organic composition," the influence of which is perceptible in all his subsequent writings; nature, he observed, presents us with only one plan of construction, the same in principle, but varied in its accessory parts. Camper's metamorphoses which demonstrated this "unity of Plan" greatly impressed Diderot and Goethe. In 1923 and 1939 some Dutch authors suggested that Camper foreshadowed Goethe's famous idea of "type" — a common structural pattern in some manner.

Petrus Camper is also known for his theory of the "facial angle" originally in connection with beauty. He was concerned with the fact that all artists painted the black Magus in the nativity with Caucasian face. He determined that modern humans had facial angles between 70° and 90°, with African angles closer to 70°. According to this technique, an angle is formed by drawing two lines: one horizontally from the nostril to the ear; and the other perpendicularly from the advancing part of the upper jawbone to the most prominent part of the forehead. He claimed that antique Greco - Roman statues presented an angle of 100° - 95°, Europeans of 90°, 'Orientals' of 80°, Black people of 70° and the orangutan of 58°, but not in an overtly racist fashion - he merely claimed that, out of all human races, Africans were most removed from the Classical sense of ideal beauty. These results were later used as scientific racism, with research continued by Étienne Geoffroy Saint - Hilaire (1772 – 1844) and Paul Broca (1824 – 1880).

Camper, however, agreed with Buffon in drawing a sharp line between human and animals (although he was misinterpreted by Diderot, who claimed that he was a supporter of the Great Chain of Being theory).

Georges Cuvier (1769 – 1832) praised his "genius eye" but criticized him for keeping himself to simple sketches ("Camper porta, pour ainsi dire en passant, le coup d'œil du génie sur une foule d'objets intéressants, mais presque tous ses travaux ne furent que des ébauches"). Petrus Camper's main works were: Démonstrations anatomicx - pathologicœ, Amsterdam, 1760 – 1762; Dissertation sur les différences des traits du visage; Discours sur l'art de juger les passions de l'homme par les traits de son visage; Dissertation sur les variétés naturelles de l'espèce humaine.

In 1888, the son of the last female descendant of Petrus Camper petitioned the Dutch crown for a name change to honor his mother, Theodora Aurelia Louisa Camper (1821 – 1890). The petition was granted by Royal Decree No. 15; and the descendants of Abraham Adriaan Aurelius Gerard Camper - Titsingh Sr. (1845 – 1910) and Abraham Adriaan Aurelius Gerard Camper - Titsingh Jr. (1889 – 1974) live today in the United States.