Vasari relates that Ser Piero, after having tried and failed to make his son attend regular lessons, was obliged to accept his artistic vocation, sending him as apprentice to Verrocchio.

In a register dated 1472, Leonardo is listed among the members of the Company of San Luca, a Florentine confraternity founded within the sphere of the Physicians and Pharmacists Guild, a kind of artists' "labour union". While the date of Leonardo's departure from Vinci is not known for certain, it can feasibly be assumed that he began to work in Andrea Verrocchio's studio in the 1460s and that he was enrolled in the Company of San Luca around the end of the decade and not before, as shown by a parchment registry of the Company dated 1469, in which Leonardo's name does not appear.

Leonardo 's apprenticeship left its mark on him. Signs of the influence of Verrocchio are already recognizable in the redundant drapery of the Annunciation, dating from 1472.

In Leonardo's first dating drawing as well, the influence of the Florentine tradition that permeates the work of Verrocchio can be seen. It is a pen-and-ink drawing representing a landscape in the valley of the Arno, on which Leonardo wrote «day of August 5, 1473», probably because he was especially satisfied with his work and wanted to preserve the memory of it. The drawing is a typical example of the Flemish-style landscape dear to Verrocchio, who in his Baptism of Christ emulated some solutions adopted by Leonardo in the drawing of 1473, among them the rendering of a rocky wall made of squared blocks, the special attention given to the reflections of the water caught in movement, and the view fading off into the distance toward the horizon. But despite the indubitable northern influence, Leonardo's drawing shows surprising innovations as compared to both coeval and subsequent landscape scenes: the graphic application of the "aerial perspective" principle and the curving lines that seem almost to deform the landscape anticipate characteristics that were to appear recurrently in the works of Leonardo.

The vision of landscape found on folio 8P in the Uffizi is a new one. Although the northern influence so strongly felt by the Florentine artists of the time is obvious, the vast differences as compared to coeval (as well as subsequent) representations of landscape are clearly apparent. Dated August 5, 1473, the drawing bears witness to Leonardo's early interest in turning directly to nature for his art. He represents the Valdinievole and the Padule di Fucecchio as seen from Montalbano. A landscape from nature, then; where the most striking aspect is the pulsing life that the artist, long before any other, managed to instill in a landscape veduta, lyrically evoking the effects of the wind blowing over the cliffs and treetops.

In December 1478 Leonardo - as he himself stated - began to paint «two Our Ladies». The subject was one of the most popular of the time. From the workshop of Verrocchio came many paintings of the Virgin and Child of the highest poetic spirit. In Leonardo's drawing of the Child in the arms of a girlish Virgin, he faithfully follows the expressive line of the master and his circle, but imposes on the figures (portrayed with renewed naturalism) gestures that mirror the senses of the soul. He instills in them that "motion" and that "breath" which are the hallmarks of Leonardo's art, and which were determinate for the development of the "modern manner".

The "manner" was even more strongly anticipated in the preparatory sheet for the Adoration of the Magi (1481), where, albeit within the reduced dimensions of the support, we find expressed (and to the highest degree) those traits of dynamism, pathos and variety that are the cornerstones of a figurative language that was to come to the forefront some twenty years later.

In the Florence State Archive are two anonymous denunciations, one dated April 9, 1476, the other June 7 of the same year, in which Leonardo is accused of sodomy. The two deeds are precious testimony because, by identifying «Lionardo of Ser Piero da Vinci» as the one who «stays with Andrea del Verrocchio», they are at present the only documentary proof of his apprenticeship to Verrocchio. But the accusation of sodomy must not have harmed the reputation of Leonardo, considering that, in 1478, he was assigned an important public commission to paint the altarpiece in the Chapel of San Bernardo in Palazzo Vecchio, a project that was however never realised.

In those same years, Leonardo completed several paintings: the mutilated Portrait of Ginevra Benci (now in the National Gallery of Washington), commissioned of him by Bernardo Bembo and, as recalled by Leonardo himself in a note in his own hand dated 1478, "the 2 Our Ladies", one of which is probably to be identified with the Benois Madonna at the Hermitage in St. Petersburg.

Dating from slightly earlier is Verrocchio's Baptism of Christ, in which the undoubted contribution of Leonardo can be recognised: the twisting pose of the angel, constructed on three different axes, recalls some of the figures in the unfinished Adoration of the Magi, the panel painting for the high altar commissioned of Leonardo by the Augustinian monks of San Domenico in a document from 1481.