The expedition reached a maximum depth of 10,928 metres / 35,853 feet deep - 16 metres / 52 feet deeper than any previous manned dive.
The team discovered a variety of new species through their underwater experiences and collected samples.
"It is nearly indescribable how excited all of us are about achieving what we just did", Mr Vescovo said after arriving in Guam after the completion of the dives.
According to Five Deeps Expedition, their scientific team identified at least three new species of marine animal during the dive series, which also went to the bottom of the Indian, Southern and Atlantic oceans. In an unexpected title that even Vescovo wasn't expecting, he is now also the first man to discover a plastic bag and sweet wrappers at the bottom of the world's deepest trench, according to BBC.
He also saw angular metal or plastic objects - one with writing on it. "But we ignore it at our peril".
"Our goal was to build a submersible capable of repeated dives to any depth with its pedigree and security assured by third-party accreditation", said Patrick Lahey, President of Triton Submarines.
"We wanted to prove the capability of the submarine and the whole system by diving there repeatedly and really, hopefully, opening the door for science", Vescovo said.
The submarine "Limiting Factor" is prepared at a drop point above the Mariana Trench.
In total, Mr Vescovo and his team made five dives to the bottom of the trench during the expedition.
Among the discoveries made aboard the The Limiting Factor - the world's first titanium-hulled, two-person submersible to dive this far - were giant prawn-like amphipods and bottom-feeding sea cucumbers.
"It has been a monumental week for ocean exploration; we have broken world records and achieved a number of world firsts".
Regarding the new species, "Expedition, scientists are still analyzing and confirming the species details so it's too early to say", a spokesperson for The Five Deeps Expedition told IFLScience.
"Our team had to pioneer new camera systems that could be mounted on the submersible, operate at up to 10,000m below sea level and work with robotic landers with camera systems that would allow us to film Victor's submersible on the bottom of the ocean".
"What we have done was a much more technical and engineering feat, which was indeed extremely challenging with setbacks and triumphs, but it was just different". Long before that, in 1960, Jacques Piccard and Don Walsh together descended 35,813 feet into the Mariana Trench.
Movie director James Cameron then made a solo plunge half a century later in 2012 in his bright green sub.