"It's an unmitigated disaster, a catastrophe. And what's more tragic is that it's a disaster of the president's own design," said Johnson at a briefing near Eagle Pass, Texas.
Johnson added that the situation is both heartbreaking and infuriating, noting the US saw the most illegal crossings in history last month.
US media reported on Tuesday that officials documented 302,000 migrant encounters in December - the highest figure recorded in a single month.
The house speaker had explained that the trip was intended so he and company could "see firsthand" what was unfolding at the US' southern border.
Johnson led about 60 Republican lawmakers to the US-Mexico border, where officials continued to demand stricter immigration policies in exchange for backing Biden’s emergency funding request for Ukraine.
The trip to Eagle Pass, Texas, comes as the Senate engages in negotiations in hopes of striking a bipartisan deal.
The US president earlier told reporters that ensuring the border situation was properly handled was on Republicans as continued government funding remains critical to the endeavor. "They ought to give me the money I need to protect the border," he said.