Ter Stegen, 29, will see a specialist later this week in Sweden and will miss Barca's final match of the season at Eibar but hopes to be fully fit for the start of next season.
The decision comes after Barca's title hopes were officially ended on Sunday as they were beaten 2-1 by Celta Vigo at Camp Nou.
"Ter Stegen will undergo a therapeutic procedure on the patellar tendon in his right knee on Thursday in Malmo by Dr Hakan Alfredson and under the supervision of the club's medical services," Barca said in a statement.
The Germany international has made 41 appearances for Barca this season after returning from a knee problem which caused some discomfort in the previous campaign.
However, a source told ESPN that the injuries are unrelated and stressed that this week's treatment is a "complementary intervention" and not an operation, as echoed by Ter Stegen on social media.
"I have decided together with the medical team of the club that I will do a complementary intervention on my knee," he wrote on Instagram.
"I'm sad that I will miss the Euro 2020 this summer with Germany. For the first time in many years, I will be a fan at home supporting my country, I hope we win it!
"After the summer break, when we are back on the pitch, I hope to be able to play with fans once again, I miss it."
Ter Stegen has won 25 caps for his country but has struggled to dislodge Manuel Neuer as Germany's regular No. 1, with the Bayern Munich goalkeeper now certain to start between the sticks at this summer's finals.