The dataset consists of location records of the Harlequin ladybird (Harmonia axyridis) in the UK. The records span from 2004 to 2016 with three records from 2003. Records were collected from several sources with the majority coming from online recording via the Harlequin Ladybird Survey website, the UK Ladybird Survey website and the iRecord Ladybird app. Other records have come from coleopterists and from a data call for the most recent ladybird atlas (e.g. local record centres, natural history societies, county Coleoptera recorders). The records include location, date and vice county, as well as life stage and colour form where available. The arrival of the Harlequin ladybird has provided a unique opportunity to study the spread of an invasive animal from the start of the invasion process. The advancements in modern technology, in particular the internet, has also provided new opportunities for recording and has enabled engagement with a far wider audience than was previously possible. This has allowed the ladybird surveys to deal efficiently with large volumes of data and verify and validate submitted records quickly. The data authors are extremely grateful to the many thousands of people across Britain who have contributed their ladybird findings to the UK Ladybird Survey.