Barca waltzed to the La Liga title while also winning the Copa del Rey for the 30th time as they thrashed Sevilla 5-0 in the final.
That was their fourth successive Copa del Rey title while the gap to second-placed Atletico Madrid at the top of La Liga stood at 14 points.
But for all their dominance in Spain, Barcelona couldn’t convert in the Champions League as they were knocked out at the quarter-final stage by Roma.
That was despite winning the first leg 4-1 at the Nou Camp, with a 3-0 Roma victory in the Italian capital enough for the Giallorossi to progress on away goals.
Barcelona have strengthened their squad as they aim to improve on last season, with Malcom, Clement Lenglet, Arturo Vidal and Arthur all coming through the door.
And having been dumped out of Europe early last season, Messi is hoping the new signings can help Barca knock Real Madrid off their European perch.
The Argentinian has also admitted the Champions League disappointment outweighed the joy of winning the double.
“We have a great squad to get excited about and those who have come in will help us to get better.
“Last season was really good as we did the double but we all felt bad about how it went in the Champions League.
“We promise that this season we will do all we can to bring that trophy back to Camp Nou.”
Messi was recently named the new Barcelona captain following the departure of club legend Andres Iniesta.
He got his reign as skipper off to a good start on Sunday, helping his side to the Supercopa trophy as they beat Sevilla 2-1 on Sunday.
Messi then got his first goal as captain as Barca saw off Boca Juniors at the Nou Camp to win the Joan Gamper trophy.
And Messi, 31, has admitted it’s a great honour to be named the new captain by Ernesto Valverde.
He added: “It’s a source of great pride to be captain. I know what it means to wear the armband.
“I am lucky to have had great role models such as [Carles] Puyol, Xavi and the great Andres whom we will miss this season.”