| IB Results Release Ceremony | 5 Jan |
| Y1 – IB2 School Camp | 08 Jan – 09 Jan |
| Y1 Induction Ceremony | 16 Jan |
| IGCSE Results Release | 16 Jan |
| Chinese New Year Celebration | 16 Feb |
| Lohei Lunch | 27 Feb |
| Hwa Chong Founders Day Prize-Giving Ceremony | 13 Mar |
| #ExperienceHCIS Open House 2025 | 11 Apr |
| Y1 – IB1 Mid-Year Examinations | 23 Apr – 08 May |
Y1 – Y4 Sabbatical Programme / Internationalism Trips IB1 CAS Trip |
18 May – 28 May 18 May – 24 May |
| Y1 – IB2 Parent-Teacher Interaction | 29 May |
| Experiential Camp | 2 Jun |
| IB2 Mid-Year Examinations | 29 Jun – 03 Jul |
| HCIS Uni Fair | 15 Jul |
| The Voice of HCIS | 06 Aug |
| HCIS Gives Back | 07 Aug |
| Y4 (IGCSE) Preliminary Examinations | 18 Aug – 02 Sep |
| Y1 – IB2 Parent-Teacher Interaction | 28 Aug |
| IB2 Preliminary Examinations | 31 Aug – 02 Sep, 14 Sep – 25 Sep |
| Teachers’ Day Celebration | 03 Sep |
| IB1 End-of-Year Examinations | 14 Sep – 25 Sep |
| IGCSE Graduation Ceremony | 25 Sep |
| IB2 Graduation Ceremony | 09 Oct |
| IB Examinations | TBC |
| Y1 – Y4 End-of-Year Examinations | 22 Oct – 05 Nov |
| Innofest | 18 Nov |