The writer of the series that features the detective Charlie Parker posted profits last year of €215,815, on top of the €150,423 recorded in 2015.
The cashpile at his Bad Dog Books Ltd slipped to €178,439, but accumulated profits reached €987,529 and intangible assets surged from €400,000 to €1m.
A graduate of Trinity College Dublin, Mr Connolly is a frequent presence on national radio and has been a regular on bestseller lists since his debut novel Every Dead Thing almost 18 years ago.
Figures from Nielsen BookScan show he has sold €13.5m worth of books in Ireland and the UK, selling 1.55m copies in the much larger UK market and 256,377 copies here.
Nielsen BookScan captures around 80% of book sales and the breakdown shows that Mr Connolly had £9.4m (€10.7m) in sales in the UK and €2.89m sales here.
Authors however, only receive a small fraction of sales revenues through royalties, as the income is shared between the publisher, printer, retailer, and agent.
The accounts show for Bad Dog Books Ltd that in spite of consistently strong sales, Mr Connolly has so far taken little by way of pay from the firm, sharing €37,434 with a fellow director.
In a recent interview, he said he relishes engaging with his readers. “The mere fact that you’ve written a book and that someone has reached out back to you is really important. There’s something quite lovely about that. You think: that’s why I’m doing this.”