The UK will pay France £8m more a year under a revised deal to try to stop people crossing the English Channel in small boats.
The money will pay for increased surveillance of French beaches, while UK police officers will also be able to observe patrols within France.
It is thought French officers patrolling the coast will rise from about 250 to 350 over five months.
PM Rishi Sunak said he was "confident" the crossings could be brought down.
However, he warned there was no "single thing" that could "fix" the situation, promising "even greater cooperation" with France in the months ahead.
Labour leader Sir Keir Starmer called the deal a "small step in the right direction," but said more needed to be done to tackle people smuggling.
The government is coming under increasing pressure to reduce journeys across the Channel, which have risen to record levels this year.
More than 40,000 people have crossed in small boats so far this year, including 1,800 this weekend alone, according to official figures.
Under the new agreement, signed by Home Secretary Suella Braverman in Paris, the UK will pay France £63m this year, up from £55m last year.
It will cover:
investment in drones, night vision equipment, and CCTV in French ports to try and prevent crossings
funding for detection dogs at ports to identify people trying to enter the UK in lorries
investment in reception and removal centres in France
UK observers will be embedded in French control rooms, and French observers embedded in UK control rooms, to help inform each other's deployments.
Home Secretary Suella Braverman told MPs the deal was a "very good platform" for deeper collaboration in the future.
"I'm not going to overplay this agreement," she said, adding: "Is it going to solve the problem on its own? It won't, but I do encourage everybody to support the deal we have secured."
