High-risk neuroblastoma (NB) currently presents significant clinical challenges. MYCN and ALK, which are often involved in high-risk NB, lead to increased replication stress in cancer cells, providing options for therapeutic exploitation. We previously identified an ATR/ALK inhibitor combination as an effective therapeutic approach in two independent genetically modified mouse NB models. Here, we identify an underlying molecular mechanism, in which ALK signalling leads to phosphorylation of ATR and CHK1, supporting an effective DNA damage response. The importance of ALK inhibition is supported by mouse data, in which monotreatment with ATRi resulted in a robust initial response, but subsequent relapse, in contrast to a 14-day ALKi/ATRi combination treatment that resulted in robust and sustained responses. Finally, we show that the remarkable response to the 14-day combined ATR/ALK inhibition protocol reflects a robust differentiation response in the tumour, reprogramming tumour cells to a neuronal/Schwann cell lineage identity. Our results identify a unique ability of ATR inhibition to trigger neuroblastoma differentiation and underscore the importance of further exploring combined ALK/ATR inhibition in NB, particularly in high-risk patient groups with oncogene-induced replication stress.