Celtic's net bank debt stood at just £130,000 on December 31 - down from more than £7million 12 months previously, according to the club's interim report.
Celtic's turnover increased by 71% to just over £50million in the final six months of the year, with operating expenses up by 30% to almost £37million.
The period in question saw Celtic play 19 home games, three more than the previous year and, crucially, in the Champions League group stages rather than the Europa League, which more than offset income lost by the loss of liquidation-hit Rangers from the Clydesdale Bank Premier League.
Chairman Ian Bankier revealed the team's run to the last 16 of the Champions League - in which they host Juventus in the first leg tomorrow - had "significantly impacted" on the results.
A breakdown of the income showed that "multimedia & other commercial activities" had raised £21.6million, up from £5million on the same six-month period in 2011.
Revenue from "football and stadium operations" (£18.6million) and merchandising (£9.8million) both jumped by about £2million.
The SPL champions also made an increased profit from transfer activity, which centres on buying young talent with a sell-on potential, despite maintaining spending levels at about £4.5million.
Bankier said: "Such investment and player development initiatives have further enhanced profitability, with a profit from transfer activity of £5.2m, largely as a consequence of the sale of Ki Sung Yueng to Swansea, in comparison to £3.15m last year.
"Nevertheless, we have managed to strike a prudent balance between trading successful, valuable assets and retaining key talent to enhance our prospects of football success."
Bankier added: "Our success on the park and the maintenance of our robust business model has provided stability in a challenging environment.
"The second half of the 2012/13 financial year is expected to follow a similar trading pattern to recent years, but buoyed by onfield success including participation in the UEFA Champions League."
Bankier added: "The increase of £5.76m in the level of receivables from 31 December 2011 to £11.34m is primarily a result of an increase in amounts due in instalments from player sales conducted in previous transfer windows and payments due from UEFA in relation to UCL group stage participations."
