| IB Results Release | 18 Dec 2024 |
| IB Results Release Ceremony | 06 Jan |
| Y1 – IB2 School Camp | 09 – 10 Jan |
| Y1 Induction Ceremony | 17 Jan |
| IGCSE Results Release | 23 Jan |
| Chinese New Year Celebration | 28 Jan |
| Lohei Lunch | 07 Feb |
| Hwa Chong Founders Day Prize-Giving Ceremony | 14 Mar |
| #ExperienceHCIS Open House 2025 | 05 Apr |
| Y1 – IB1 Mid-Year Examinations | 28 Apr – 09 May |
Y1 – Y4 Sabbatical Programme / Internationalism Trips IB1 CAS Trip | 20 May – 29 May 19 May – 25 May |
| Y1 – IB2 Parent-Teacher Interaction | 30 May |
| Experiential Camp | 2 Jun |
| IB2 Mid-Year Examinations | 30 Jun – 04 Jul |
| The Voice of HCIS | 06 Aug |
| HCIS Gives Back | 07 Aug |
| Opening Ceremony of Annex Expansion, Sports Complex and Homecoming | 08 Aug |
| Y4 (IGCSE) Preliminary Examinations | 19 Aug – 03 Sep |
| Y1 – IB2 Parent-Teacher Interaction | 22 Aug |
| IB2 Preliminary Examinations | 01 Sep – 03 Sep, 15 Sep – 26 Sep |
| Teachers’ Day Celebration | 04 Sep |
| IB1 End-of-Year Examinations | 15 Sep – 26 Sep |
| IGCSE Graduation Ceremony | 30 Sep |
| IB2 Graduation Ceremony | 10 Oct |
| IB Examinations | TBC |
| Y1 – Y4 End-of-Year Examinations | 23 Oct – 06 Nov |
| Innofest | 18 Nov |