The Catalan giants headed to the Basque Country with two points to their name from the last six on offer, but they managed to return to winning ways thanks to goals from Luis Suarez and Jordi Alba in either half.
Victory for Barca, made easier following the sending-off of Fabian Orellana 66 minutes in, also ensures that they have equalled their club-record run of games unbeaten in the Spanish top flight, matching the 31 set by Pep Guardiola's class of 2011.
Beaten just once in their last 12 league games and fresh on the back of a 5-1 win against Sevilla here in their last home outing, Eibar were always expected to give Barca a run for their money.
Ivan Ramis also sent a headed effort down the middle for Ter Stegen to collect, before Barca opened up their European-chasing opponents to open the scoring against the run of play.
Orellana, responsible for two of the goals in the win over Sevilla, came closest to a first-half response when sending a side-footed shot dipping over Ter Stegen and back against the crossbar.
Messi squandered a big opportunity to add a killer second before the break, sending Suarez's pull-back against the post with two covering defenders on the line to beat.
Eibar, now beaten in all eight La Liga meetings with Barca, were continuing to probe away in search of a leveller and perhaps should have had it when Takashi Inui was picked out in space 12 yards out, only to send his snapshot wide.
The visitors were struggling for creativity for large parts of the second period and turned to Philippe Coutinho - a surprise sub this afternoon - for the final 25 minutes of the contest.
Coutinho's introduction coincided with key man Orellana's dismissal for Los Armeros, coming after he booted the ball away to be shown a second yellow card.
Jose Luis Mendilibar was also sent to the stands on his 100th match in charge of the Basque outfit as matters started to boil over at a packed Ipurua.
Not until 10 minutes from time did the first on-target shots of the second half arrive - Messi being denied by Dmitrovic with his lofted attempt and Inui failing to get the beating of Ter Stegen on the turn.
A big block was required from Gerard Pique to stop Inui finding a way through late on, and that gave Alba the opportunity to finally kill things off at the death, tucking the ball between post and defender after Messi's saved shot rebounded into his path.
EIBAR (4-2-3-1): Dimitrovic; Pena, Ramis (Lomban 46'), Arbilla, Jose Angel; Dani Garcia, Diop (Escalante 74'); Orellana, Jordan (Charles 83'), Inui; Kike
BARCELONA (4-4-2): Ter Stegen; S.Roberto (Semedo 90'), Pique, Umtiti, Alba; Busquets, Rakitic, Paulinho (Vidal 74'), Iniesta (Coutinho 63'); Messi, L.Suarez