Among his early paintings are some altarpieces and religious themes. In 1734, he completed frescoes in the walls and ceiling of the hall in Ca' Sagredo, representing the Death of the giants. Henceforward, his work would lead him to be viewed in the future as the Venetian William Hogarth, painting subjects and events of everyday life in Venice. The gallant interior scenes reflect the 18th century's turn towards the private and the bourgeois.
Many of his paintings show Venetians at play, such as the depiction of the crowd of genteel citizens awkwardly gawking at a freakish Indian rhinoceros (see image). This painting chronicles Clara the rhinoceros brought to Europe in 1741 by a Dutch sea captain and impresario from Leyden, Douvemont van der Meer. This rhinoceros was exhibited in Venice in 1751. There are two versions of this painting, nearly identical except for the unmasked portraits of two men in Ca' Rezzonico version. Ultimately, there may be a punning joke to the painting, since the young man on the left holds aloft the sawed off horn (metaphor for cuckoldry) of the animal. Perhaps this explains the difference between the unchaperoned women.
Other paintings chronicle the daily activities such as the gambling parlors (Riddoti) that proliferated in the 18th century. In some, the insecure or naive posture and circumstance, the puppet-like delicacy of the persons, seem to suggest a satirical perspective of the artists toward his subjects. Nearly half of the figures in his genre paintings are faceless, hidden behind Venetian Carnival masks. Like Crespi before him, Longhi was commissioned to paint seven canvases documenting the seven Catholic sacraments.
A paraphrase of Bernard Berenson states that "Longhi painted for the Venetians passionate about painting, their daily lives, in all dailiness, domesticity, and quotidian mundane-ness. In the scenes regarding the hairdo and the apparel of the lady, we find the subject of gossip of the inopportune barber, chattering of the maid; in the school of dance, the amiable sound of violins. It is not tragic... but upholds a deep respect of customs, of great refinement, with an omnipresent good humor distinguishes the paintings of the Longhi from those of Hogarth, at times pitiless and loaded with omens of change".