The former Brexit secretary, Conservative MP for Haltemprice and Howden, welcomed the latest financial support for Universal Credit in the Budget, but said the welfare reform must be "properly funded" and called for extra cash in future to help single parents and others.
He declared the policy on student loans has "failed" and advised ministers to pursue a "proper graduate contribution system" and move away from loans altogether, which he said would have a "liberating psychological impact" on young people.
On housing, the Tory MP said as a "party of aspiration" they "must do better" by ensuring home ownership is available to a "whole new generation" and suggested using landowner gains to help make properties more affordable.
As Mr Davis neared the end of his speech, Labour former minister Kevan Jones expressed his frustration at his refusal to take interventions and said in a point of order: "I don't want to interrupt (Mr Davis) in his leadership speech, but the point is this is supposed to be a debate."
Speaking during day three of the Budget debate, Mr Davis said extra funding is needed to help those "in most need", including single parents, couples without children and people who should not be economically dependent on their partners.
He told the Commons: "We must make sure that in future that they're not left wanting by subsequent changes so it will need further funding beyond what has already been promised in this Budget, and I'll certainly be watching that in the future."
Addressing education and training, Mr Davis said: "The cost of university education, plus the confusion around the financing of it, act as a disincentive to taking a university education.
"I'm afraid the policy on student loans has failed.
"Almost half the loans will never be repaid, they are a falsehood in the national accounts. Crucially, the loan system has failed to deliver a market in university education."
Pointing at the Labour frontbench, he added: "And the honourable member on the frontbench shouldn't be smiling, they basically invented this system, and created the problems I'm about to talk about."
He added the "least valuable courses at the worst universities" cost the same as the "most valuable" at the "most prestigious" university, adding: "At least some of the money has gone not into world-class research but overpaying some pretty second-rate vice-chancellors.
"The whole system needs to be revamped, turned into a proper graduate contribution system, with honest accounting, clear rules and no retrospective changes in the interest rates or other terms.
"In the long-run, we should move away from loans altogether, with a liberating psychological impact that this would have on young people."
Mr Davis added the Government needs to do more on housing as he warned home ownership levels are "plummeting", with many young people fearing they will not have a property to call their own.
He said: "As a party of aspiration, we must do better. Help to Buy is failing, it's not increasing supply of housing, rather it's increasing the cost of new homes by 15% and inflating the bonuses of developers.
"Help to Buy should be scrapped immediately. We need to dramatically increase the supply of new homes and make those homes attractive and affordable."
Mr Davis said garden villages, towns and cities were perhaps the best ideas mooted, suggesting half of the gains for landowners should be "funnelled in a way to reduce the price of the final house" in a bid to create "proper" affordable housing.
He said: "However we do it, we, the Conservative Party, have to grasp this problem and solve it. This party has for over 50 years been the party of a home-owning democracy. We need to once more make home ownership available to a whole new generation."
Concluding, Mr Davis said governments of all parties have failed to deliver on nearly all of their "enormous" social mobility claims over the last 50 years, adding he wants Theresa May's administration to "deliver on social mobility, delivers on the real value of a capitalist economy".