The work and pensions secretary said the infrastructure investment fund could finance essential projects including flood defences, a national fibre-optic broadband network and Crossrail Two.
The money would come from issuing new government bonds, Mr Crabb said.
Bond yields have fallen since the Brexit vote, lowering borrowing costs.
"The cost of borrowing is incredibly low. Spending government money on infrastructure has therefore never been more affordable," Mr Crabb said.
Mr Crabb announced his plan in conjunction with Business Secretary Sajid Javid, whom he plans to appoint as chancellor if he wins the leadership election.
The duo said they would also bring forward current infrastructure plans, including the electrification of the TransPennine Manchester to Leeds rail route which was put on hold last year.
They plan to issue up to £20bn of long-dated bonds each year for five successive years to create the fund.
It would also be used to invest in social housing, school buildings and new prisons, Mr Crabb said.
Mr Javid claimed the plan could create "hundreds of thousands" of new jobs.
Mr Crabb is the latest Tory leadership contender to set out his stall.
Rival candidate Michael Gove, currently justice secretary, has vowed to cut immigration by blocking EU free movement and spend an extra £100m a week on the NHS if he wins.
Current frontrunner Home Secretary Theresa May has promised to reconcile the Remain and Leave sides and "govern for the whole country".
The leadership contest was triggered by David Cameron's decision to step down by October after the UK voted to leave the EU in last month's referendum.
Mr Crabb and the four other candidates - Mr Gove, Mrs May, Andrea Leadsom and Liam Fox - will take part in a series of ballots of the party's 330 MPs, starting on Tuesday.
The two most popular will then go on to a vote of the wider party membership, with the result due on 9 September.
Tory leadership contender Stephen Crabb has pledged to create a £100bn "Growing Britain Fund" if elected.