Amazon sales soared 40% in the three months ending June, while Apple saw a surge in purchases of its iPhones and other hardware.
At Facebook, the number of people on its platforms, which include WhatsApp and Instagram, jumped by 15%.
The gains come as the firms face scrutiny over their size and power.
At a hearing in Washington on Wednesday, lawmakers grilled the companies about whether they were abusing their dominance to quash rivals, noting the sharp contrast between their fortunes and many other firms.
Their positions are likely to become even stronger, as the pandemic pushes even more activity online, said Congressman David Cicilline, the Democrat who leads the committee.
"Prior to the coronavirus pandemic, these corporations already stood out as titans in our economy," he said.
"In the wake of COVID-19, however, they are likely to emerge stronger and more powerful than ever before."
The gains weren't a surprise to analysts - though just how well many of the firms did, was.
At Amazon, the quarterly profit of $5.2bn (£4bn) was the biggest since the company's start in 1994 and came despite heavy spending on protective gear and other measures due to the virus.
"This is an exceptional quarter on all fronts under extreme circumstances," Moody's vice president Charlie O'Shea said of Amazon's blockbuster rise.