Joseph Willock 19, was given a rare start by Arsenal manager Unai Emery and he delivered the expectations at Bloomfield Road.
Arsenal should have taken the lead on two occasions inside the first 10 minutes but Edward Nketiah missed glorious chances from inside the box.
Willock spared his blushes in the 12th minute when he came alive in the penalty box at the right time. Arsenal won a free-kick on the edge of the area and Aaron Ramsey hit the post, but Willock reacted first and headed into the empty net.
Alex Iwobi then wasted another opportunity from close range before Willock grabbed his second after a quick break down the right wing.
Right-back Carl Jenkinson’s cross picked out Nketiah but his volley was blocked before falling to Willock. The forward tapped in at the back post to end Blackpool’s chances of a third-round shock.
The Tangerines should have responded through Liam Feeney but the winger could only fire his shot straight into the hands of Petr Cech. Joseph Willock was denied his hat-trick in the second half with the offside flag coming to Blackpool’s rescue.
He tapped in Sead Kolasinac’s cross but the left-back set off too early before cutting the ball back.
Arsenal’s third goal came eight minutes from time when Alex Iwobi tapped home after another close effort from Ramsey. The Welshman saw his shot saved but Iwobi was in the perfect position to tap home, albeit from an offside position.