I would like to inform you of my resignation.
'Dimissioni' = di-mis-SYO-ni. Four syllables; stress the third. Note: always plural in Italian.
Use this at the start of your resignation conversation with your direct manager. It is the formal, unambiguous Italian way to announce a resignation. The conditional 'vorrei' softens the delivery without any ambiguity about your intention.
In Italian, 'dimissioni' (resignation) is always plural — even when referring to one person's resignation. 'Comunicare' (to communicate/inform) is more professional than 'dire' (to say). 'Le' (formal 'Lei') maintains the appropriate register.
Ho preso la decisione di dimettermi.
I have made the decision to resign.
'Dimettersi' is the reflexive infinitive for 'to resign' — the core Italian verb
Devo comunicarle una decisione importante riguardo al mio futuro professionale.
I need to inform you of an important decision regarding my professional future.
More indirect; useful when you want to ease into the conversation
Ho deciso di lasciare l'azienda.
I have decided to leave the company.
Very direct; 'lasciare' is less formal but completely natural
In Italy, resigning must be done by written notice ('lettera di dimissioni') within specific timeframes defined by the employment contract and CCNL. Since 2016, resignations must also be submitted digitally through the government's online portal ('click day' procedure) within 7 days of the written notice — failure to do so makes the resignation legally void.