Mr. Obasanjo made the allegation while hosting the South-West women leaders at his residence in Abeokuta Monday.
He said his administration left over $25 billion to his successor, Musa Yar'adua, who raised the sum to $35 billion.
Mr. Obasanjo said he also left $40billion in Nigeria's foreign reserve account after paying the outstanding debt at the time.
He said former President Yar'adua also raised the reserves to $60billion.
Under President Jonathan, the reserves has plummeted to $40billion, Mr. Obasanjo said.
The new claims followed a series of public denunciation of Mr. Jonathan's government by the former president.
In 2014, Mr. Obasanjo repeatedly lambasted the current government, accusing the president of promoting and and tolerating corruption, and failing to provide security for Nigerians.
Mr. Obasanjo also released a book mid-December scolding the president as a self-centred politician who thinks less of the country and fraternises with corrupt and questionable characters.
In his comments on Monday, Mr. Obasanjo said he was not fighting the president, nor was Mr. Jonathan fighting him. He said he was more concerned about the interest of the country, and therefore cared less about criticisms.
"Our economy should not have been this bad. When I was leaving office about eight years ago, I left a very huge reserve after we had paid all our debts. Almost $25billion we kept in what they called excess crude. The excess from the budget we were saving as reserve for the rainy days. When we left in May 2007, the reserve was said to have been raised to $35billion," he said.
"But today, that reserve has been depleted! Today, that reserve has been depleted. The reserve we left when we finished paying all our debts, our debts that was about 40billion dollars, that is including debt forgiveness, the remaining debt was not more than $3billion. Our reserve after we had paid off this debt was about $45billion. As I said, they continued till the end of 2007, I heard that the reserve increased to almost $67billion before the end of the year. Our reserve now, learnt is left with around only $30billion.
"That is why the Naira has been falling against the dollar. What would now happen, I learnt if you want to buy a dollar now, it's about N192 or N195. What it means is this, what you have been buying at N150 to a dollar, now you need N192 or N195 to buy it. That is the real situation. Is there any remedy? There is, but it does not come overnight because it means we have to give up all the bad things we have been doing," Mr. Obasanjo said.
"I know that God did not create Nigeria not to be rich or great. Is it that the people he created in Nigeria are not knowledgeable enough or not intelligent enough? Or is that they don't know their rights? Our problems in Nigeria, let's look at the foundation of our leadership. In the profession I know very well, the military, what we normally say is that there are no bad soldiers but bad officers. If you see a situation where the soldiers are not doing well, we need to examine the officers in charge. So it is in the family, the community, the town and the country," he said.
He denied being against President Jonathan.
"I have no grudges against Jonathan and I think Jonathan equally has no grudges against me. I'm not quarrelling with Jonathan but all I know is that whatever is good for Nigeria, that I'm ready to die for," he said.
"I emphasize that whatever is good for Nigeria, is what I'm ready to defend with my life. Whoever, I emphasize, whoever says he would not do anything good to Nigeria, even if he says he's ready to go 'konko below', I'm ready to square it up with such a person. I say again, whoever that person may be, I want you to get that correctly. If this country is going to change for the better, it would start from the top and if it's going to be otherwise, it would start from the top, too," the former president stressed.
On the forthcoming election, Mr. Obasanjo said he's not apprehensive as being speculated, just as he advised the electorates to vote for candidates with integrity and good records.
"I have no apprehension over this coming elections. I have no fears over the forthcoming elections. I have had some little experience about this country. I was a military head of state and I was also a civilian president, so what is left?'
"So, if I talk, I know what I'm saying. Whoever wants, should listen to me and whoever feels otherwise, may turn a deaf ear. But when I'm talking, I'm talking with my understanding and intellect. I'm drawing from my experience and from what I've learnt with others and from other countries and fellow eminent citizens of the world that I relate with. But leave all of that.
"Good governance comes from voting, from selection of leaders. It is now left to you to decide who you cast your vote for because if you throw away your votes and tomorrow you are saying good governance, once you throw away your votes you have lost out. That is one. Find out the track records of achievements of those you want to vote for. What have they achieved in the past and not what they have said'.
"Truly, the price of crude has fallen, but anyone who is wise enough should know that since we depend on just one resources, and since we have no control over its pricing, we should be planning for this type of situation and the way out of it. Our inability to have reserve has brought us into this economic quagmire," he said.
Earlier in her speech, the Iyalode of Yorubaland, who led the women, noted that President Obasanjo has become a good repository of everything that makes for nationhood.
"You are the hand and eye in all the nooks and crannies of Nigeria. You are the voice everybody is waiting to hear his response on any topical issue in the public domain. We believe we are in the right place to discuss with you some knotty issues bleeding our hearts as we have seen you as a beacon of hope and lights for the nation", Ms. Lawson told Obasanjo.
On state of the nation, the women said they were concerned about current happenings in the country, going by the current atmosphere of fear and uncertainty.
She said the nation is plagued by insecurity, economic downturn, poverty, corruption, among other challenges.
"The unabated nefarious activities of the insurgents which have placed us as a people on the throes of war is worrisome to us, because womenfolk is the most affected. Countless Nigerian women have lost their lives, husbands, children, relatives and sources of livelihood as a result of the despicable acts of killing and wanton destruction by the Boko Haram insurgents," she said.