| Date: | 27 February – 5 March (ATP) 6 – 12 March (ITF) |
| Edition: | 12th (ATP) 1st (ITF) |
| Category: | ATP Challenger Tour ITF Women's Circuit |
| Prize Money: | $50,000+H (ATP) $25,000 (ITF) |
| Surface: | Hard |
| Location: | Yokohama, Japan |
| Champms: |  Yūichi Sugita |
| Champws: | Akiko Omae |
| Champmd: | Marin Draganja / Tomislav Draganja |
| Champwd: | Ayaka Okuno / Erika Sema |
| Before Year: | 2015 |
The 2017 Keio Challenger was a professional tennis tournament played on hard courts. It was the twelfth (ATP) and first (ITF) editions of the tournament and part of the 2017 ATP Challenger Tour and the 2017 ITF Women's Circuit. The tournament offered $50,000+H in prize money for the men and $25,000 prize money for the women. It took place in Yokohama, Japan between 27 February and 5 March 2017 for the men's edition and between 6 and 12 March 2017 for the women's.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| Japan | Yūichi Sugita | 114 | 1 | |
| Henri Laaksonen | 122 | 2 | ||
 Korea, Republic of | Lee Duck-hee | 135 | 3 | |
| Japan | Go Soeda | 136 | 4 | |
| Grega Žemlja | 150 | 5 | ||
 Belgium | Ruben Bemelmans | 152 | 6 | |
 China | Zhang Ze | 157 | 7 | |
 Australia | Andrew Whittington | 164 | 8 |
The following players received wildcards into the singles main draw:
Sora Fukuda Masato Shiga Kaito Uesugi Yosuke WatanukiThe following player received entry into the singles main using a protected ranking:
The following player received entry into the singles main draw as a special exemption:
The following players received entry from the qualifying draw:
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| Japan | Miyu Kato | 201 | 1 | |
 United Kingdom | Laura Robson | 207 | 2 | |
| Japan | Akiko Omae | 229 | 3 | |
| Japan | Mayo Hibi | 230 | 4 | |
| Japan | Shiho Akita | 246 | 5 | |
| Japan | Junri Namigata | 256 | 6 | |
 Kazakhstan | Galina Voskoboeva | 257 | 7 | |
| Japan | Kyōka Okamura | 259 | 8 |
The following players received wildcards into the singles main draw:
Sumina Eshiro Hayaka Murase Megumi Nishimoto Suzuho OshinoThe following players received entry from the qualifying draw:
Haruna Arakawa Erina Hayashi Miyabi Inoue Haruka Kaji Rio Kitagawa Mai Minokoshi Ramu Ueda Aki YamasotoSee main article: 2017 Keio Challenger – Men's singles.
Yūichi Sugita def. Kwon Soon-woo 6–4, 2–6, 7–6(7–2). Akiko Omae def. Mayo Hibi 7–5, 6–2.See main article: 2017 Keio Challenger – Men's doubles.
Joris De Loore / Luke Saville 4–6, 6–3, [10–4]. Ayaka Okuno / Erika Sema def. Kanako Morisaki / Minori Yonehara, 6–4, 6–4.