The 34-year-old striker is the oldest player to score a hat-trick in the competition since Hungarian great Ferenc Puskas in 1965 for Real Madrid against Feyenoord.
He is also the first player to net four times in a Champions League match since Cristiano Ronaldo against Malmo five years ago.
Both teams were already qualified for the last 16 before kick-off, but Giroud made the most of a rare start, scoring with his left foot, his right foot and his head to see Chelsea through as group winners, also slotting in a penalty.
The France international sent out a message to his manager Frank Lampard, with Timo Werner and Tammy Abraham seemingly above him in the pecking order, by making the absolute most of only his second start of the season.
Lampard will now be able to rest players for the final group game against Krasnodar at Stamford Bridge, with his side looking to improve on last season’s run to the last 16, where they were well beaten by eventual winners Bayern Munich.
Giroud wasted little time in putting Chelsea ahead, collecting Kai Havertz’s clever pass before cutting inside and bending a fine finish into the far corner in the eighth minute.
Sevilla were left frustrated as they saw two penalty appeals for handball turned down.
In the 20th minute, claims that Christian Pulisic handled were waved away by referee Artur Soares Dias after he checked the pitchside monitor.
The hosts had another penalty shout turned down following a lengthy VAR delay after an Ivan Rakitic free-kick struck the Chelsea wall.
Aside from those nervy moments, Lampard’s Blues were the more threatening, with Antonio Rudiger seeing a header cleared off the line before Alfonso Pastor kept out Pulisic’s low drive.
The home side started the second half brightly, as Jesus Navas picked out Nemanja Gudelj with a clever pass, but the Serbian international fired narrowly over.
Chelsea doubled their advantage in the 54th minute, though, as Giroud boosted his case for more game time further by latching onto Mateo Kovacic’s pass and clipping the ball over the Sevilla goalkeeper.
But he was not finished there, completing his first Champions League hat-trick since a treble against Olympiakos for Arsenal in 2015 with a looping header from N’Golo Kante’s cross.
Giroud rounded off a virtuoso display from the spot with seven minutes to play, scoring a spot-kick he had won himself.