The preliminary results for the year ended June 30, just released, showed a drop in turnover to £51.34m, an increase in operating expenses of £1.93m and an overall loss of £7.37m against a very slight profit the year before.
The level of debt rose from £0.53m in June 2011 to £2.77m in June 2012.
Celtic are in Champions League action against Benfica tonight, having won the SPL title, and those achievements justify the figures, said the chief executive.
He said: "The club's in a decent place and we have built up over the past few years."
He continued: "We have a great foundation, a great basis to take the club forward.
"There will be challenging times ahead but we are prepared for that."
The sale of South Korean international Ki Sung-Yueng to Swansea for an undisclosed fee thought to be around £6m and rewards of qualification for the Champions League group stage were not part of the preliminary results, having occurred after the time period.
"You can see that we have registered a loss, to June 30, 2012, of just under £7.4million," Lawwell added.
"Now that loss, we could have eliminated if we had taken the opportunity to sell one or two players in January and cut the wage bill, but our main priority was to win the SPL and hopefully give us a pathway into the Champions League."
He said that the club's debt level "at under £3m - is very comfortable for a club of Celtic's size and revenue streams."
lOlympic silver medallist Michael Jamieson will be a special guest at Celtic's home clash with Benfica tonight and the British 200m breast stroke swim record holder will appear on the park at half-time.