Giovanni di Buccio di Leonardello, who was born in Orvieto, was first documented in his native city in 1347.  All of his known surviving work is in his native city.  This largely involved the mosaics of the facade of the Domo. 

Orvieto

Work in the Duomo

Frescoes of the Cappella del Corporale (1356)

The frescoes of the Cappella del Corporale were commissioned in 1356 from Giovanni di Buccio di Leonardello and Ugolino di Prete Ilario.  However, Giovanni soon left the team to concentrate on the mosaics of the facade.  

Mosaics of the Facade

Giovanni di Buccio di Leonardello was involved in the decoration of the facade of the Duomo in 1360-6:

1. Baptism of Christ (1360)
   

2. 

   Andrea Orcagna and Giovanni di Buccio di Leonardello collaborated on the cartoon for the Baptism of Christ in the gable over the left door in 1360.  Nello da Roma completed the mosaic of the Annunciation to St Anna in 1362.  The Opera del Duomo waited for a year before paying for these mosaics because there were concerns for their stability: in 1363, Ugolino di Prete Ilario pronounced them "perfectum, et bonum et pulchrum"(perfect and good and fair).  These original mosaics no longer survive.
   

3. 
   

4. Birth of the Virgin (1365-6)
   

5. An inscription records that Ugolino di Prete Ilario designed this fresco in the gable over the right door in 1365 and that it was executed by Giovanni di Buccio di Leonardello.  It was replaced by a copy in 1786.  The original (which has been heavily restored) was given to Pope Pius IV and then sold in 1890 to the Victoria and Albert Museum, London.
   

6. Assumption of the Virgin (1366)
   

7. 

   
   

8. These heavily restored scenes above the central door still bore the signature of Giovanni di Buccio di Leonardello and the date 1366 in the 19th century.  Angels transport the Virgin in a mandorla while the Apostles to the sides witness the scene.
   

Works in San Giovenale

Annunciation and Nativity (14th century)

This damaged fresco under the aedicule on the right wall of San Giovenale (to the right of the side entrance) is attributed variously to Ugolino di Prete Ilario  or Giovanni di Buccio di Leonardello. 

Christ and the Evangelists (14th century)

These damaged frescoes in tondi in the vaults of the Cappella di San Sabino in San Giovenale are attributed to Giovanni di Buccio di Leonardello.