| Challenger Francavilla | 04/30 13:00 | 29 | [219] Pedro Sousa v Alessandro Giannessi [121] | 6-3,7-6 | |
| Challenger Francavilla | 04/29 14:50 | 28 | [225] Stefano Travaglia v Alessandro Giannessi [121] | 7-5,4-6,2-6 | |
| Challenger Francavilla | 04/28 14:55 | 27 | Ruben R. Hidalgo v Alessandro Giannessi | Retired | |
| Challenger Francavilla | 04/28 14:45 | - | Ruben R Hidalgo v Alessandro Giannessi | 6-4,4-6,0-0 | |
| Challenger Francavilla | 04/27 10:30 | 26 | [346] Lorenzo Sonego v Alessandro Giannessi [121] | 6-3,4-6,4-6 | |
| Challenger Francavilla | 04/25 16:20 | 25 | [206] Stefanos Tsitsipas v Alessandro Giannessi [121] | 6-7,4-6 | |
| ATP Monte Carlo Qual | 04/15 14:00 | 45 | [70] Damir Dzumhur v Alessandro Giannessi [121] | 6-3,7-5 | |
| Challenger Barletta | 04/14 12:25 | 27 | [161] Lukáš Rosol v Alessandro Giannessi [121] | 2-6,6-3,6-3 | |
| Challenger Barletta | 04/13 10:00 | 26 | [200] Nikola Milojevic v Alessandro Giannessi [121] | 1-6,3-6 | |
| Challenger Barletta | 04/11 14:00 | 25 | [208] Riccardo Bellotti v Alessandro Giannessi [121] | 3-6,3-6 | |
| Davis Cup | 04/09 14:40 | 27 | [199] Joris De Loore v Alessandro Giannessi [122] | 4-6,6-7 | |
| Challenger Santiago | 03/07 23:30 | 25 | [349] Simone Bolelli v Alessandro Giannessi [121] | Retired | |
| ATP Sao Paulo | 03/02 17:50 | 26 | Alessandro Giannessi v Fabio Fognini | 6-7,6-7 | |
| ATP Sao Paulo | 02/28 15:30 | 25 | Rogerio Dutra Silva v Alessandro Giannessi | 4-6,3-6 | |
| ATP Sao Paulo Qual | 02/26 14:00 | - | Alessandro Giannessi v Guido Andreozzi | Retired | |
| ATP Sao Paulo Qual | 02/25 15:30 | 26 | Alessandro Giannessi v Federico Coria | Retired | |
| ATP Rio De Janeiro Qual | 02/18 12:00 | 45 | Marco Cecchinato v Alessandro Giannessi | 7-6,6-7,6-2 | |
| ATP Buenos Aires | 02/15 21:45 | 26 | Alessandro Giannessi v Pablo Carreno Busta | 1-6,6-4,4-6 | |
| ATP Buenos Aires | 02/14 22:50 | 25 | Rogerio Dutra Silva v Alessandro Giannessi | 7-5,6-7,4-6 | |
| ATP Buenos Aires Qual | 02/13 18:30 | 46 | Dusan Lajovic v Alessandro Giannessi | 3-6,6-3,1-6 | |
| ATP Buenos Aires Qual | 02/11 18:45 | 45 | Roberto Carballes Baena v Alessandro Giannessi | 4-6,4-6 | |
| ATP Quito | 02/07 21:55 | 25 | Alejandro Falla v Alessandro Giannessi | 6-4,6-3 | |
| Challenger Koblenz | 01/19 10:00 | 26 | Nils Langer v Alessandro Giannessi | 6-2,6-0 | |
| Challenger Koblenz | 01/17 11:15 | 25 | Franko Skugor v Alessandro Giannessi | 4-6,6-7 | |
| Australian Open 2017 Qual | 01/11 04:20 | 44 | Alessandro Giannessi v Jan Šátral | 6-7,6-7 | |
| ATP Doha | 01/03 17:30 | 25 | Tomas Berdych v Alessandro Giannessi | 7-6,6-2 | |
| ATP Doha Qual | 01/01 12:30 | 46 | Mirza Basic v Alessandro Giannessi | 4-6,2-6 | |
| ATP Doha Qual | 12/31 08:00 | 45 | Mousa Shanan Zayed v Alessandro Giannessi | 2-6,1-6 | |
| Challenger Ortisei | 11/13 12:00 | 29 | Alessandro Giannessi v Stefano Napolitano | 4-6,1-6 | |
| Challenger Ortisei | 11/12 14:35 | 28 | Lorenzo Sonego v Alessandro Giannessi | 6-3,5-7,4-6 |
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.