The 24-year-old is set to be sidelined for six months after tests revealed he would need surgery following anterior cruciate ligament damage sustained when making a defensive tackle during the closing stages of the third-round FA Cup win over Tottenham at the Emirates Stadium.
The club have rallied behind Walcott, who is expected to undergo an operation next week once the swelling on his left knee has eased, with messages of support flooding in from fans and fellow professionals alike.
Arsenal full-back Jenkinson offered his own words of encouragement for the England international, who is now set to miss out on the World Cup finals in Brazil.
"If anybody is going to come back better and stronger, it is Theo. He is incredibly focused and mentally he is a very strong character," Jenkinson told www.Arsenal.com.
"Theo will be fine, I have no doubts about that. I am disappointed that we have lost him for the rest of the season because he is a massive player for us and brings us something unique.
"It is tough to see one of your friends out for a long period of time.
"You wouldn't wish it on anybody and it is probably the worst news we have had all season."
Jenkinson added: "He had only just come back from a previous injury and had been scoring goals for fun, so from both points of view it it terrible news.
"But Theo is a very strong guy and while it may take a bit of time to take it all in, he will just get on with things and fingers crossed the time flies by, for his sake and for ours."