This study investigates the acquisition of the third person pronoun keoi5 佢 with inanimate referents in post-verbal position (henceforth, KEOI) in Hong Kong Cantonese. Following a linguistic analysis of KEOI vis-à-vis its equivalents it in English and tā 它 in Mandarin Chinese, we conducted a corpus-based study on the use of KEOI in 9 Cantonese-English bilingual children (1;03–4;06) and 3 Cantonese monolingual children (1;10–2;09) in naturalistic settings. Results show that Cantonese-speaking children mainly used KEOI as a canonical object of verbal predicates expressing irrealis bounded disposal events, indicating their early sensitivity to the aspectual properties of KEOI-clauses. While monolingual children were consistently adult-like in using KEOI, bilingual children produced unbounded KEOI-clauses unattested in their monolingual peers and the adults. They also used higher rates of realis KEOI-clauses and demonstrated interchangeable use between KEOI and it in code-mixed utterances. Our findings lend support to the proposal that KEOI marks bounded disposals with irrealis results or states. Input and language experience are shown to influence the acquisition of KEOI-clauses, with cross-linguistic influence of English likely induced by the interplay among ambiguity of input in Cantonese, extensive exposure to English and regular processing of the English pronouns.