Premier League clubs not competing in Europe enter this evening's cup draw.
The Gills will be ball number 13 in the southern section for Wednesday evening's second round Carabao Cup draw.
Steve Evans' side clinched a dramatic penalty shootout win over Crawley Town at the People's Pension Stadium on Tuesday, with Harvey Lintott scoring the crucial tenth spot kick.
The club reached the third round of the competition last season, eventually losing to Stoke City at the bet365 Stadium.
The draw will be made, live on Twitter, following the conclusion of the live televised fixture between Leyton Orient and Queens Park Rangers.
Numbers for the draw are as follows:
NORTH
1. Accrington Stanley
2. Aston Villa
3. Barrow
4. Bolton Wanderers
5. Burnley
6. Crewe Alexandra
7. Derby County
8. Doncaster Rovers
9. Everton
10. Huddersfield Town
11. Leeds United
12. Morecambe
13. Newcastle United
14. Oldham Athletic
15. Preston North End
16. Rochdale
17. Sheffield United
18. Shrewsbury Town
19. Stoke City
20. Sunderland AFC
21. Wigan Athletic
22. Wolverhampton Wanderers
23. Blackpool/Middlesbrough
24. Nottingham Forest/Bradford City
SOUTH
1. AFC Bournemouth
2. AFC Wimbledon
3. Arsenal
4. Birmingham City
5. Brentford
6. Brighton & Hove Albion
7. Cambridge United
8. Cardiff City
9. Cheltenham Town
10. Crystal Palace
11. Forest Green Rovers
12. Fulham
13. Gillingham
14. Millwall
15. Newport County
16. Norwich City
17. Plymouth Argyle
18. Southampton
19. Stevenage
20. Swansea City
21. Watford
22. West Bromwich Albion
23. Wycombe Wanderers
24. Burton Albion/Oxford United
25. Coventry City/Northampton Town
26. Leyton Orient/Queens Park Rangers