The 42-year-old actor, who is originally from Australia but has spent the past 17 years living in the US starring in shows such as Law and Order and The Sopranos, said that he had to hire a dialect coach to help him rediscover his accent for Australian drama series The Slap.
LaPaglia told The Sunday Telegraph: "I am ashamed, it was weirdly tough. By the end of the day I'd be, like, 'I got it' - and then I'd wake up and be f**king American again."
He also said that he is very excited to be making his Australian TV debut but said that he has done things the wrong way around.
LaPaglia explained: "I kind of did things as backwards. I wasn't really established as an actor in Australia and most actors establish themselves there and then come to America.
"Five years ago I started thinking about working back in Australia. I'm like most actors, lazy, so I didn't do anything about it and then a couple of years ago I got approached by an agent and we hooked up and [The Slap] came together."
LaPaglia, who stars alongside Melissa George and Sophie Okonedo in the ABC drama, admitted that his brother - Without a Trace star Anthony - was "definitely an influence" when deciding which career path to follow.
BBC Four recently picked up the rights to air The Slap in the UK.
Watch ABC's trailer for The Slap below (Video contains strong language):