The Jags ended their prolonged barren run in style at Tynecastle as first-half goals from Lyle Taylor and Aaron Taylor-Sinclair moved them 20 points clear of the bottom-of-the-table Jambos.
After seeing relegation play-off spot rivals Kilmarnock and Ross County both pick up points in recent weeks, Thistle found their form at just the right time as they moved back above the Staggies in the standings and to within touching distance of St Mirren in the Premiership table. Boss Archibald said: "It was vital to win. We haven't won in such a long time.
"Ross County won on Saturday and have put a wee run together so it was vital that we got a victory.
"You never feel confident until the whistle goes.
"We done something today that we haven't done that often this season, we ground out a result.
"We didn't play our best stuff by any manner of means but we have played great stuff all year and not got our rewards.
"I thought we showed a different side to our game and went and battled our corner and defended well."
Thistle went into the capital clash looking for their first points of 2014 after they were left empty-handed from a spirited showing against champions Celtic on Wednesday afternoon.
It took just 13 minutes for the Jags to break the deadlock and pile more pressure on the beleaguered Jambos as Taylor netted his first goal for the club following his loan switch from Sheffield United, picking up a Kallum Higginbotham flick-on and holding off Dylan McGowan to fire past keeper Jamie MacDonald.
Before a frantic opening period had come to a close, Archibald's men were already well on their way to a huge victory.
This time Taylor-Sinclair was the goal hero as he headed home Higginbotham's corner to the delight of the vocal Jags travelling support behind MacDonald's goal.
Gary Locke's side never really looked like launching a comeback in the second half as they struggled to threaten, with a long-range effort from Callum Tapping that cracked Scott Fox's crossbar the closest they came to a goal.
Even a late red card for Stuart Bannigan after he picked up two quickfire bookings was not enough to upset Thistle as they claimed a priceless three points.
The Jags face County, Killie, St Johnstone and the Saints before the end of the month and Archibald is looking onwards and upwards after they extended their lead over the Jambos.
He said: "I would be very disappointed if we give that 20 points to Hearts up.
"Hopefully today's victory gives us a lot of confidence and we can go and start looking at the teams above us and try and drag them into us.
"There are two or three round about us and we can maybe make it interesting."