| Singles | |
|---|---|
| 2018 Amex-Istanbul Challenger | |
| Champion |  Corentin Moutet |
| Runner-up | Quentin Halys |
| Final score | 6–3, 6–4 |
Malek Jaziri was the defending champion but chose not to defend his title.
Corentin Moutet won the title after defeating Quentin Halys 6–3, 6–4 in the final.
Thomas Fabbiano (semifinals) Corentin Moutet (champion)
Adrián Menéndez Maceiras (first round) Quentin Halys (final) Constant Lestienne (second round)
Oscar Otte (second round)
Tallon Griekspoor (quarterfinals)
Lucas Miedler (quarterfinals)| Semifinals | Final | ||||||||||||
| 1 | Thomas Fabbiano | 3 | 6 | 4 | |||||||||
| 4 | Quentin Halys | 6 | 4 | 6 | |||||||||
| 4 | Quentin Halys | 3 | 4 | ||||||||||
| 2 | Corentin Moutet | 6 | 6 | ||||||||||
| Antoine Hoang | 6 | 5 | 0 | ||||||||||
| 2 | Corentin Moutet | 2 | 7 | 6 | |||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 1 | T Fabbiano | 6 | 6 | ||||||||||||||||||||||||
| Alt | H Grenier | 3 | 2 | 1 | T Fabbiano | 3 | 6 | 6 | |||||||||||||||||||
 V Šafránek | 1 | 4 | B Bonzi | 6 | 1 | 4 | |||||||||||||||||||||
| B Bonzi | 6 | 6 | 1 | T Fabbiano | 3 | 6 | 6 | ||||||||||||||||||||
 D Yevseyev | 63 | 4 | M Viola | 6 | 2 | 4 | |||||||||||||||||||||
| M Viola | 77 | 6 | M Viola | 6 | 6 | ||||||||||||||||||||||
| D Masur | 6 | 3 | 65 | 5 | C Lestienne | 3 | 1 | ||||||||||||||||||||
| 5 | C Lestienne | 0 | 6 | 77 | 1 | T Fabbiano | 3 | 6 | 4 | ||||||||||||||||||
| 4 | Q Halys | 6 | 6 | 4 | Q Halys | 6 | 4 | 6 | |||||||||||||||||||
| WC | N Kuhn | 3 | 4 | 4 | Q Halys | 77 | 65 | 6 | |||||||||||||||||||
| A Nedovyesov | 6 | 6 | A Nedovyesov | 64 | 77 | 4 | |||||||||||||||||||||
| WC |  A Metreveli | 3 | 4 | 4 | Q Halys | 6 | 3 | 77 | |||||||||||||||||||
| Q |  Y Hossam | 6 | 6 | 7 | T Griekspoor | 4 | 6 | 63 | |||||||||||||||||||
| WC |  A Yüksel | 3 | 2 | Q | Y Hossam | 3 | 2 | ||||||||||||||||||||
| Q | TK Wang | 4 | 1 | 7 | T Griekspoor | 6 | 6 | ||||||||||||||||||||
| 7 | T Griekspoor | 6 | 6 | ||||||||||||||||||||||||
| First round | Second round | Quarterfinals | Semifinals | ||||||||||||||||||||||||
| 8 | L Miedler | 7 | 3 | ||||||||||||||||||||||||
| SE | E Couacaud | 5 | 0r | 8 | L Miedler | 6 | 77 | ||||||||||||||||||||
| Q | T van Rijthoven | 67 | 2 | E Benchetrit | 3 | 62 | |||||||||||||||||||||
| E Benchetrit | 79 | 6 | 8 | L Miedler | 4 | 5 | |||||||||||||||||||||
| M Janvier | 6 | 3 | 4 | A Hoang | 6 | 7 | |||||||||||||||||||||
| A Hoang | 4 | 6 | 6 | A Hoang | 60 | 6 | 6 | ||||||||||||||||||||
 G Oliveira | 6 | 2 | 6 | G Oliveira | 77 | 3 | 2 | ||||||||||||||||||||
| 3 | A Menéndez Maceiras | 3 | 6 | 2 | A Hoang | 6 | 5 | 0 | |||||||||||||||||||
| 6 | O Otte | 6 | 6 | 2 | C Moutet | 2 | 7 | 6 | |||||||||||||||||||
 J Ward | 3 | 3 | 6 | O Otte | 3 | 4 | |||||||||||||||||||||
| WC | E Kırkın | 2 | 6 | 4 | C İlkel | 6 | 6 | ||||||||||||||||||||
| C İlkel | 6 | 4 | 6 | C İlkel | 64 | 3 | |||||||||||||||||||||
 J Menezes | 7 | 6 | 2 | C Moutet | 77 | 6 | |||||||||||||||||||||
| Q | A Çelikbilek | 5 | 1 | J Menezes | 4 | 0 | |||||||||||||||||||||
| T Kamke | 4 | 2 | 2 | C Moutet | 6 | 6 | |||||||||||||||||||||
| 2 | C Moutet | 6 | 6 | ||||||||||||||||||||||||
Norbert Gombos was the defending champion but lost in the first round to Corentin Moutet.
Dominic Thiem was the defending champion, but lost in the quarterfinals to Fernando Verdasco.
Two-time defending champion Rafael Nadal successfully defended his title, defeating Stefanos Tsitsipas in the final, 6–2, 6–1. By winning the title, Nadal retained the ATP no. 1 singles ranking. It was Nadal's record-extending eleventh Barcelona Open title and his 20th ATP 500 title overall, equaling Roger Federer's record. It was Tsitsipas' maiden ATP final.
Félix Auger-Aliassime was the defending champion and successfully defended his title.
David Ferrer was the defending champion, but lost in the second round to Casper Ruud.
Leonardo Mayer was the defending champion, but lost in the final to Nikoloz Basilashvili, 4–6, 6–0, 5–7. This was Basilashvili's first ATP World Tour title, as well as the first ATP title won by a Georgian player since Alexander Metreveli.
Uladzimir Ignatik was the defending champion but lost in the second round to Ugo Humbert.
Jason Kubler was the defending champion but chose not to defend his title.
Vasek Pospisil was the defending champion but chose not to defend his title.
Jordan Thompson was the defending champion but chose not to defend his title.
Grégoire Barrère was the defending champion and successfully defended his title.
Ričardas Berankis was the defending champion but lost in the semifinals to Kamil Majchrzak.
Luca Vanni was the defending champion but chose not to defend his title.
Félix Auger-Aliassime was the defending champion but chose not to defend his title.
Matteo Berrettini was the defending champion, but withdrew with an ankle injury before the tournament began.
Enzo Couacaud was the defending champion but chose not to defend his title.
Corentin Moutet was the defending champion but chose not to defend his title.
Hubert Hurkacz was the defending champion but chose not to defend his title.
Roberto Bautista Agut was the defending champion, but chose to compete in the ATP Cup instead.
Corentin Moutet was the defending champion but chose not to defend his title.