| Challenger Barcelona | 10/04 10:30 | 27 | [166] Alessandro Giannessi v Filippo Baldi [158] | 5-7,6-0,6-1 | |
| Challenger Barcelona | 10/03 10:30 | 26 | [177] Filip Horanský v Alessandro Giannessi [166] | 6-7,7-6,4-6 | |
| Challenger Barcelona | 10/02 09:00 | 25 | [328] Ivan Nedelko v Alessandro Giannessi [166] | 1-6,4-6 | |
| Challenger Florence | 09/26 14:05 | 26 | [80] Philipp Kohlschreiber v Alessandro Giannessi [168] | 4-6,6-4,6-3 | |
| Challenger Florence | 09/25 13:55 | 25 | [381] Jules Okala v Alessandro Giannessi [168] | 3-6,0-6 | |
| Challenger Biella | 09/20 12:50 | 27 | [108] Alejandro Davidovich Fokina v Alessandro Giannessi [171] | 6-2,6-1 | |
| Challenger Biella | 09/19 14:10 | 26 | [196] Marco Trungelliti v Alessandro Giannessi [171] | 6-7,1-6 | |
| Challenger Biella | 09/17 10:10 | 25 | Giacomo Dambrosi v Alessandro Giannessi | 4-6,4-6 | |
| Challenger Szczecin | 09/11 11:10 | 25 | Pawel Cias v Alessandro Giannessi | 6-2,6-0 | |
| Challenger Janov | 09/02 11:25 | 24 | [150] Alessandro Giannessi v Viktor Galovic [224] | Retired | |
| Challenger Como | 08/31 12:10 | 28 | [266] Facundo Mena v Alessandro Giannessi [150] | 6-2,1-6,6-2 | |
| Challenger Como | 08/30 13:20 | 27 | [150] Alessandro Giannessi v Dmitry Popko [236] | 7-6,4-6,6-4 | |
| Challenger Como | 08/29 13:25 | 26 | [150] Alessandro Giannessi v Sebastian Ofner [167] | 6-4,6-2 | |
| Challenger Como | 08/28 08:00 | 25 | [150] Alessandro Giannessi v Johan Tatlot [343] | 1-6,6-4,6-3 | |
| US Open | 08/22 16:25 | 45 | [201] Constant Lestienne v Alessandro Giannessi [149] | 6-3,6-0 | |
| US Open | 08/20 15:00 | 44 | [278] Jeffrey John Wolf v Alessandro Giannessi [149] | 6-2,5-7,2-6 | |
| Challenger Sopot | 07/30 13:25 | 25 | Alessandro Giannessi v Aleksandre Metreveli | 6-4,3-6,4-6 | |
| Challenger Praha | 07/24 10:35 | 25 | [152] Alessandro Giannessi v Andrea Collarini [313] | 0-6,2-6 | |
| Challenger San Benedetto | 07/21 19:15 | 29 | [163] Alessandro Giannessi v Renzo Olivo [330] | 7-5,6-7,4-6 | |
| Challenger San Benedetto | 07/20 17:55 | 28 | [119] Andrej Martin v Alessandro Giannessi [163] | 7-6,1-6,6-7 | |
| Challenger San Benedetto | 07/19 17:45 | 27 | [163] Alessandro Giannessi v Andrea Arnaboldi [219] | 5-7,6-3,7-6 | |
| Challenger San Benedetto | 07/18 17:30 | 26 | [163] Alessandro Giannessi v Manuel Guinard [346] | 6-3,4-6,6-3 | |
| Challenger San Benedetto | 07/17 19:15 | 25 | Alessandro Giannessi v Christopher O'Connell | 7-6,6-3 | |
| Challenger Perugia | 07/12 17:00 | 27 | [160] Alessandro Giannessi v Albert Ramos-Vinolas [99] | Retired | |
| Challenger Perugia | 07/11 11:50 | 26 | [160] Alessandro Giannessi v Facundo Bagnis [161] | Retired | |
| Challenger Perugia | 07/09 10:20 | 25 | [160] Alessandro Giannessi v Mario Vilella Martinez [269] | 6-7,6-2,6-3 | |
| Wimbledon | 06/24 14:15 | 44 | [213] Yannick Hanfmann v Alessandro Giannessi [163] | 7-5,7-5 | |
| Challenger Parma | 06/19 10:05 | 25 | [370] Julian Lenz v Alessandro Giannessi [162] | 6-1,6-4 | |
| Challenger Poznan | 06/07 09:30 | 27 | [395] Andrea Vavassori v Alessandro Giannessi [164] | 7-6,6-1 | |
| Challenger Poznan | 06/06 11:10 | 26 | [164] Alessandro Giannessi v Daniel Masur [251] | 7-6,4-6,6-3 |
Alessandro Giannessi (* 30. května 1990 La Spezia) je italský profesionální tenista hrající levou rukou. Ve své dosavadní kariéře na okruhu ATP World Tour nevyhrál žádný turnaj. Na challengerech ATP a okruhu ITF získal do září 2016 šest titulů ve dvouhře a sedm ve čtyřhře.
Na žebříčku ATP byl ve dvouhře nejvýše klasifikován v dubnu 2012 na 126. místě a ve čtyřhře pak v říjnu 2013 na 171. místě. Trénují ho Gabrio Castrichella a Eduardo Infantino.
V italském daviscupovém týmu neodehrál žádné utkání.