| Date: | 7–13 January 2018 |
| Edition: | 126th |
| Category: | ATP World Tour 250 series / WTA Premier |
| Draw: | 32S / 16D |
| Surface: | Hard |
| Location: | Sydney, Australia |
| Venue: | NSW Tennis Centre |
| Champms: |  Daniil Medvedev |
| Champws: | Angelique Kerber |
| Champmd: |  Łukasz Kubot /  Marcelo Melo |
| Champwd: |  Gabriela Dabrowski /  Xu Yifan |
| Before Name: | Apia International Sydney |
The 2018 Sydney International was a joint 2018 ATP World Tour and 2018 WTA Tour tennis tournament, played on outdoor hard courts in Sydney, New South Wales (NSW). It was the 126th edition of the tournament and took place at the NSW Tennis Centre in Sydney. It was held from 7 January through 13 January 2018 as part of the Australian Open Series in preparation for the first Grand Slam of the year. Venus Williams played the event for the first time in 17 years, 20 years after her maiden appearance.[1]
| Event | W | F | SF | QF | Round of 16 | Round of 32 | width=85 | Q | width=85 | Q3 | width=85 | Q2 | width=85 | Q1 |
| Men's singles | 250 | 150 | 90 | 45 | 20 | 0 | 12 | 6 | 0 | 0 | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Men's doubles | 0 | |||||||||||||
| Women's singles | 470 | 305 | 185 | 100 | 55 | 1 | 25 | 18 | 13 | 1 | ||||
| Women's doubles | 1 |
| Event | W | F | SF | QF | Round of 16 | Round of 321 | width=85 | Q3 | width=85 | Q2 | width=85 | Q1 |
| Men's singles | $83,650 | $44,055 | $23,865 | $13,595 | $8,010 | $4,745 | $2,135 | $1,070 | ||||
| Men's doubles* | $25,410 | $13,360 | $7,240 | $4,140 | $2,430 | |||||||
| Women's singles | $137,125 | $73,201 | $39,132 | $20,970 | $11,245 | $6,140 | $3,210 | $1,705 | $945 | |||
| Women's doubles* | $42,850 | $22,900 | $12,510 | $6,365 | $3,460 |
| width=70 | Country | width=175 | Player | Rank1 | Seed |
|---|---|---|---|---|---|
 Spain | Albert Ramos Viñolas | 23 | 1 | ||
 Luxembourg | Gilles Müller | 25 | 2 | ||
 Argentina | Diego Schwartzman | 26 | 3 | ||
 Italy | Fabio Fognini | 27 | 4 | ||
 France | Adrian Mannarino | 28 | 5 | ||
| Philipp Kohlschreiber | 29 | 6 | |||
 Bosnia and Herzegovina | Damir Džumhur | 30 | 7 | ||
| Mischa Zverev | 33 | 8 |
The following players received wildcards into the singles main draw:
The following players received entry into the singles main draw as special exempts:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
Filip Krajinović → replaced by 
Ričardas Berankis
Kei Nishikori → replaced by Viktor Troicki| Country | Player | Country | Player | Rank1 | Seed | |
|---|---|---|---|---|---|---|
| Poland | Łukasz Kubot | Brazil | Marcelo Melo | 3 | 1 | |
| Jean-Julien Rojer |  Romania | Horia Tecău | 15 | 2 | ||
| Spain | Feliciano López | Spain | Marc López | 44 | 3 | |
 India | Rohan Bopanna | France | Édouard Roger-Vasselin | 44 | 4 |
The following pairs received wildcards into the doubles main draw:
| width=70 | Country | width=175 | Player | Rank1 | Seed |
|---|---|---|---|---|---|
| Spain | Garbiñe Muguruza | 2 | 1 | ||
| Venus Williams | 5 | 2 | |||
| Jeļena Ostapenko | 7 | 3 | |||
 United Kingdom | Johanna Konta | 9 | 4 | ||
| France | Kristina Mladenovic | 11 | 5 | ||
| Sloane Stephens | 13 | 6 | |||
| Anastasija Sevastova | 16 | 8 | |||
The following players received wildcards into the singles main draw:
The following players received entry from the qualifying draw:
The following players received entry as lucky losers:
Anastasia Pavlyuchenkova → replaced by Ekaterina Makarova Peng Shuai → replaced by Lara Arruabarrena| Country | Player | Country | Player | Rank1 | Seed | |
|---|---|---|---|---|---|---|
| Latisha Chan |  Czech Republic | Andrea Sestini Hlaváčková | 6 | 1 | ||
| Czech Republic | Lucie Šafářová | Czech Republic | Barbora Strýcová | 21 | 2 | |
| Canada | Gabriela Dabrowski | China | Xu Yifan | 34 | 3 | |
| Kiki Bertens |  Sweden | Johanna Larsson | 39 | 4 |
The following team received entry as alternates:
See main article: 2018 Sydney International – Men's singles.
Daniil Medvedev def. 
Alex de Minaur, 1–6, 6–4, 7–5See main article: 2018 Sydney International – Women's singles.
Ashleigh Barty, 6–4, 6–4See main article: 2018 Sydney International – Men's doubles.
Łukasz Kubot / Marcelo Melo def. Jan-Lennard Struff / Viktor Troicki, 6–3, 6–4.See main article: 2018 Sydney International – Women's doubles.
Gabriela Dabrowski / Xu Yifan def. Latisha Chan / Andrea Sestini Hlaváčková, 6–3, 6–1