French President Emmanuel Macron named Lecornu, a former defence minister, to the post last month.
But the largely unchanged cabinet Lecornu unveiled late on Sunday sparked fierce criticism across the political spectrum.
“There can be no return to stability without a return to the polls and the dissolution of the National Assembly,” National Rally leader Jordan Bardella said after Lecornu resigned.
The premier had faced the daunting task of finding approval in a deeply divided parliament for an austerity budget for next year.
Lecornu’s two immediate predecessors, François Bayrou and Michel Barnier, were ousted by the legislative chamber in a standoff over the spending plan.
France’s public debt has reached a record high, official data showed last week.
France’s debt-to-GDP ratio is now the European Union’s third highest after Greece and Italy, and is close to twice the 60 percent permitted under EU rules.
Previous governments had rammed the last three annual budgets through parliament without a vote, a method allowed by the constitution but deeply criticised by the opposition.
But Lecornu promised last week to ensure lawmakers were able to vote on the bill.
France has been mired in deadlock since Macron gambled on snap parliamentary elections in the middle of last year in the hopes of bolstering his authority.
The move backfired, leaving the Macron-friendly bloc in the assembly in a minority
