The Spanish city's council realised in 2016 that Gaudi's spectacular church had never been granted planning permission.
They awarded the licence to a committee in charge of finishing construction for 4.6 million euros ($5.2 million) after construction first began in 1882.
The unfinished basilica is one of Spain's biggest tourist attractions and was named a UNESCO World Heritage Site in 2005.
According to the committee in charge of finishing construction of the not-yet-completed basilica, designer Antoni Gaudi had asked the town hall of Sant Marti, for a building permit in 1885 but never got an answer.
#SagradaFamília construction licence approved, allowing Antoni #Gaudí’s project to continue. More info on our blog ➡ https://t.co/OPuubJ8eTZ pic.twitter.com/S75tH06LRF
— La Sagrada Família (@sagradafamilia) June 7, 2019