Informal caregiving constitutes the mainstay of a society’s care supply. Motivations for caring and continuing to provide care are crucial to understanding the nature of caregiver experiences and their relationship with the person/people they support. This systematic review of qualitative evidence examines determinants of motivations and willingness to provide informal care. One hundred and five qualitative studies published before August 2019 and fitting the inclusion criteria were identified, 84 of them pertaining to cultural and societal motivations for caregiving. Grounded theory-based, thematic synthesis was conducted. Cultural and societal factors strongly underpinned motivations and willingness for informal caregiving. The main cultural motives for caregiving were cultural values and beliefs encompassing the ethnocultural context of the caregiving role, culture-specific norms, cultural and spiritual beliefs, illness beliefs and socialisation. Societal norms and perceived expectations, such as gendered roles, norms and expectations of caregiving, and perceptions of health and social care services further shaped caregiver motivations and willingness to provide care. These meta-synthesis findings contribute towards novel understandings about the cultural and societal aspects shaping informal care provision. These findings bear important implications for theory, research, policy and practice; all of which contributing to the issue of the sustainability of informal care from a ‘macro’ perspective.