The Russian oligarch bought the Blues on July 1, 2003 for £140 million from then-owner Ken Bates, bringing an end to Bates' 21-year reign at Stamford Bridge.
But as that era ended, another one began as Chelsea went about snapping up some of the finest talent in Europe in Abramovich's pursuit of glory.
Of course, Chelsea were no slouches.
They had just qualified for the Champions League for a second time. And prior to Abramovich's arrival, the club had also tasted success in the FA Cup (1997 and 2000), League Cup (1998) and UEFA Cup Winners' Cup (1998).
But their new Russian owner took the Blues onto another level that saw even more trophies flood into the Stamford Bridge trophy cabinet, including back-to-back Premier League titles.
It's estimated that Abramovich has spent £2 billion during his decade as Chelsea owner (via The Sun) and in that time the Blues have brought no less than 70 players.
There have been some greats—and some flops, we might add—but of the talent the Blues have acquired with the help of their owners' wealth, who would make it into an all-time Roman Abramovich XI?
It's a question that's a little harder to answer than one would imagine.
Frank Lampard and John Terry would walk into an all-time Chelsea XI, let alone an Abramovich XI. But the English duo were already at the club before the Russian arrived, so they are omitted on that basis.
Nonetheless, our XI team (below) is crammed with international talent and would give new Premier League champions Manchester United more than a run for their money.
Petr Cech has been an outstanding servant for Chelsea, while Branislav Ivanovic and Ashley Cole at right-back and left-back are a pretty formidable combination.
David Luiz and Ricardo Carvalho bring a good blend of spirit and poise. In front of them Michael Ballack and Claude Makelele offer good defensive protection from midfield and a good source for building attacks.
Joe Cole of the 2008-09 campaign at Chelsea was arguably one of England's best midfielders at the time, so he makes our starting lineup on that basis. The performances of Eden Hazard and Juan Mata this season outline just why Abramovich has spent around £55 million on them.
They will no doubt achieve much in their Chelsea careers.
As the lone striker, has there been anyone better than Didier Drogba in the world let alone at Chelsea in the past decade? The Ivorian was phenomenal for the Blues and his legacy will far out stretch most.
But what do you think? This is the opinion of just one Bleacher Report writer—so what's yours?
Use the comments section below or continue the debate on Twitter @garryhayes