In a record-breaking clash, the Sky Blues edged Perth Glory 3-2 at nib Stadium on Thursday night.
Glory came from three goals down in the first half to set up a grandstand finish courtesy of a stunning late brace from second half subsitute, Adam Taggart (72', 89').
But the Sky Blues held on to grab an unassailable position at the top of the table - 11 points clear of Newcastle Jets who have three games to play.
Sydney have now won four premierships, more than any other club in the league.
And Brazilian hitman Bobo, who scored a brace (29', 39'), brought his campaign tally to 24, surpassing Bruno Fornaroli for the most goals scored in a regular A-League season.
Arnold told Fox Sports post-match: "We just created history. "It's the first time in 25 years (including the NSL) that a team's gone back-to-back.
"It's what we've been driving at for a long, long time and I thought the first half was outstandiing.
"But you know, we're not finished, we've still got records to chase. That's how you motivate the boys here, especially in a salary cap system with no bonuses.
"We've got a busy program ahead and it's about getting the players on the field at the right time and enure that we go into the finals with some momentum now."
Glory remain one point off the top six with their finals hopes balanced on a knife's edge.
The visitors got on the front foot early when Brandon O'Neill's lofted pass found Bobo whose shot was parried into the path of Adrian Mierzejewski for the opener on 12 minutes.
Bobo doubled the advantage from the penalty spot after Dino Djulbic brought down Matt Simon in the box, before Mierzejewski turned provider to set up the Brazilian's second of the night.
"A lot of people don't respect what we've done to be the most consistent side over two seasons," Arnold said. "We're 11 points clear now and we finished last season 17 points clear.
"One thing I think that's gone missing is that we've had a turnover in the squad - losing Danny Vukovic, (Filip) Holosko, (Milos) Dimitrijevic,Rhyan Grant - with an ACL at the start of the season. We had to do it the hard way as well with some changes.
"But look I couldn't be prouder of the boys, they're a fantastic group of players...And we're not finished yet. At the end of the day we've got Adelaide at home next game, we've got Melbourne Victory to finish off and then it's all about going into the finals with some great performances."
Sydney came close to throwing away their win in the second half as Glory .
"They were prepared to lose 8-0 and threw four up the front," Arnold said.
"We had out chances on the break, didn't punish them with a fourth, and Adam Taggart scored two great goals."
Sydney are in ACL action next Tuesday, away to Suwon. The Sky Blues currently sit last in their group.