Figures lodged with the Companies Office by the Mayo man show that Brill Management Ltd recorded the loss after more than quadrupling profits to €1.26m in 2011.
The firm had accumulated profits of €1.32m at Nov 30, 2012. Its cash reduced during the year from €671,244 to €587,485.
Mr Walsh has managed Ireland’s most successful ever boy bands — Boyzone and Westlife. He has overseen Jedward’s rise to stardom and is currently re-launching the career of former Westlife singer Shane Filan.
Mr Walsh — who turned 61 last Sunday — is due to feature in the forthcoming series of The X Factor for a record-breaking 10th year.
In a recent interview, he said the new series will be his last. “I’m happy this is going to be my last year.”
While Brill Management made a loss last year, the rent the firm paid to Mr Walsh for its premises at Appian Way, Ranelagh, Dublin, increased almost three-fold, from €136,500 in 2011 to €362,279 last year.
The abridged accounts do not provide a revenue figure or salaries paid.
However, the amount paid in PAYE/PRSI last year more than tripled, from €39,903 to €126,120, indicating higher staff costs.
On Nov 28 last year, The Sun agreed to pay Mr Walsh €500,000 in damages and €180,000 in costs arising from publishing a false story.
The unemployed dance teacher at the centre of the report was jailed for concocting a story that he was sexually assaulted by Mr Walsh. Leonard Watters, aged 25, a father-of-two from Woodview, Navan, Co Meath, was given an 11-month term, with five months suspended, at Dublin Circuit Court.
Separately, last year, Mr Walsh said in a newspaper interview that he lost around €10m as a result of the property crash.
Commenting on six homes, including four in Dublin, one in London, and one in Miami, he said: “Everything I bought here is worth half of what it was. We were all hyped in the property boom, we were all told it was never going to end.”
Mr Walsh also has a sizeable art collection that includes works by David Hockney and Andy Warhol.