Mikel Arteta hails 'magic night' as Arsenal hold their nerve to reach quarter-finals
Leandro Trossard's first-half goal made it 1-1 on aggregate after Porto had edged the first leg, but Arsenal could not conjure a winner in normal and extra time before they triumphed 4-2 on penalties.
It is the first time the north Londoners have been in the quarter-finals since 2010, after which they suffered seven successive exits in the last-16 before a six-season absence from Europe's elite club competition.
"A magic night. We expected a really tough opponent. It's very difficult to generate momentum and that's credit to (Porto)," Arteta told reporters.
"It's a huge experience for us. We had to do it as well through penalties. Credit to (goalkeeper) David (Raya) who had some difficult moments to start but showed incredible determination and stood up and got rewarded."
Loanee Raya had returned to the starting lineup after being unable to play against his host club Brentford on Saturday as Arsenal won an eighth successive Premier League match to move top of the table with 10 games left.
The Spaniard proved the hero on a tense night as he kept out Galeno's penalty to spark wild celebrations.
"Obviously it's a great feeling for me personally, first time in the Champions League and for the club to get into the quarter-finals for the first time in so many years," Raya said.
"We've worked a lot on penalties this year and all the hard work with the goalie coach and the team has paid off. A great moment personally and collectively.
"This means everything. You play football for these kind of things and I'm lucky to be playing for Arsenal."
There was a mood of euphoria at the end and Arteta said the fans had helped his young side get over the line.
"We're starting to create an unbelievable energy in the stadium, we were all pushing to get it done and together we have done it," he said. "We absolutely love (the fans), the energy they gave, how positive they were, how they contributed.
"They made us win, it's as simple as that."