Not much occurred in the first 45 minutes of action, but Ivan Rakitic, Lionel Messi (2) and Luis Suarez (2) all scored in the second period as Barcelona - who again move 19 points clear of reigning champions Real Madrid - continued their march towards the title.
As for Barcelona, neither Paulinho nor Andres Iniesta were deemed fit enough to start, meaning that Sergi Roberto and Andre Gomes were given midfield spots. Ruben Semedo came into right-back, but fit-again Samuel Umtiti was only on the bench.
An end-to-end first 15 minutes saw both teams commit plenty of players in the final third of the field, but Betis were having the better moments, with Joaquin the next to miss Ter Stegen's post following a counter-attack.
Barcelona had to wait until the 26th minute for their first serious look at the Betis goal; it came from Luis Suarez as the forward fed Roberto inside the Betis box, but the Spaniard lifted the ball over the crossbar from close range.
Rakitic then fired into the arms of Betis goalkeeper Antonio Adan moments later, before Messi hit the side-netting just past the 30-minute mark as Barcelona started to find space.
Betis were resilient at the back, however, and the two teams headed down the tunnel at 0-0 following a half that produced few clear chances for either side.
Fabian Ruiz tested Ter Stegen with a long-range strike in the 56th minute, but it was league leaders Barcelona that made the breakthrough just before the hour.
Luis Suarez's through-pass released Rakitic, and the Croatian stayed calm to slide the ball under Adan for his first La Liga goal of the campaign.
The visitors then doubled their lead in the 64th minute when Messi collected a clever pass from Sergio Busquets before swivelling and finding the back of the net with a powerful finish.
Betis were all over the place at the back, and Barcelona made it 3-0 in the 69th minute when Luis Suarez volleyed a Rakitic cross into the back of the net as the Uruguay international scored in his seventh straight league appearance.
Messi's second of the match in the 80th minute made it 4-0 as the Argentine danced past a couple of challenges before calmly slotting the ball under Adan.
Barcelona were not finished though, and added a fifth in the 89th minute when Messi found Luis Suarez, who picked out the top corner with a super finish to cap an incredible second-half performance from the league leaders.
BETIS (4-3-3): Adan; Francis, Mandi, Feddal, Durmisi; Garcia (Boudebouz 77'), Fabian (Camarasa 88'), Guardado; Tello, Leon (Castro 73'), Joaquin
BARCELONA (4-4-2): Ter Stegen; Semedo, Pique, Vermaelen (Umtiti 43'), Alba; Busquets (Deulofeu 81'), Rakitic, Roberto, Gomes (Paulinho 65'); Messi, Suarez