The Doctor of Philosophy (PhD) — classified under the Australian Qualifications Framework (AQF) as a Level 10 qualification and categorised as a 'High Cost' program within the Mixed Field Programmes funding cluster — is the highest academic degree conferred by Australian universities. It is a research-intensive qualification in which candidates undertake a substantial, original, and independent research project under the supervision of two or more academic experts, culminating in a thesis (typically 80,000–100,000 words) that makes a genuine contribution to knowledge in the chosen discipline. The 'High Cost' and 'Mixed Field' designation reflects the significant resource investment required by universities to support doctoral research across a broad spectrum of disciplines — including humanities, social sciences, sciences, engineering, education, arts, health, and interdisciplinary fields — where specialised laboratories, archives, fieldwork, and expert supervision are necessary. Programs typically take three to four years of full-time study, though part-time enrolment over up to eight years is also available at most institutions.

The PhD is designed for high-achieving graduates who are driven by intellectual curiosity, a desire to advance human knowledge, and ambition to become leaders in their field. Candidates come from a wide variety of backgrounds: recent Honours or Master's graduates who wish to enter academia or research careers, mid-career professionals seeking deep expertise to solve complex industry problems, and international students drawn to Australia's world-class research infrastructure and funding ecosystem. Australia is the fourth most popular destination for doctoral study globally, with more than 50,000 doctoral candidates currently enrolled across its universities. Employers of PhD graduates span academia, government agencies, medical research institutes, defence, technology companies, consulting firms, financial services, the energy sector, and non-government organisations — reflecting the breadth of disciplines covered under the Mixed Field Programmes category.

The standard academic entry requirement for a PhD in Australia is the completion of an approved higher education qualification demonstrating research capability. This typically means a Bachelor's degree with First Class or Upper Second Class Honours (Honours IIA or above), or a Master of Philosophy (MPhil) or equivalent research master's degree from a recognised institution. Some universities also accept a coursework master's degree that included a substantial research component (such as a 25,000-word research thesis), provided the applicant achieves a minimum GPA — often around 5.65 on a 7-point scale. In all cases, the prior qualification must be relevant to the proposed research topic. Applicants who do not hold Honours or a research master's may sometimes gain entry with a combination of a postgraduate qualification and demonstrable research experience, subject to approval by the relevant dean or faculty.

In addition to academic qualifications, most Australian universities require prospective PhD candidates to identify a suitable primary supervisor whose research interests align with the proposed project before submitting a formal application. A written research proposal is a critical component of the application, setting out the research question, methodology, and anticipated contribution to the field. Supporting documentation typically includes certified academic transcripts, a curriculum vitae, a personal statement, and two or three academic referee reports. Applicants are generally not required to sit GRE or GMAT exams; however, a small number of programs in business-related fields may request GMAT scores.

For international applicants, English language proficiency must be demonstrated, with most universities requiring an IELTS Academic overall score of 6.5 (with no band below 6.0), or equivalent scores in TOEFL iBT, PTE Academic, or Cambridge C1 Advanced. Some universities set higher thresholds of 7.0 overall. Applicants who have completed their prior degree in English in an approved country may be exempt from language testing. Domestic students are generally funded through the Australian Government's Research Training Program (RTP), which covers tuition fees in full and may provide a living stipend of approximately AUD $35,000–$38,000 per year tax-free. International candidates must either hold an RTP scholarship or equivalent university-funded award, as self-funded PhD enrolment is uncommon.