"I just like what he's doing, and I'm standing behind him," Lane said.
"It's something I plan on keep on doing, until I feel like justice is being served."
Lane's decision comes less than a week after Kaepernick first sat in protest of American racial injustice and minority oppression.
Kaepernick and teammate Eric Reid took a knee during the anthem before the 49ers' game against the Chargers in San Diego on Thursday night.
Lane, 26, is in his fifth year with Seattle. He re-signed with the team during the offseason and is expected to start opposite Richard Sherman. He said he did not tell his teammates about his decision beforehand, and that Kaepernick was not a friend or acquaintance.
Asked if he's prepared to deal with the reaction to his decision, Lane said, "Yeah, I am prepared for it. And I don't mean no disrespect to anybody, but I'm just standing behind what I believe in."
Sherman said Lane had strong conviction when he made the decision to sit.
"Any time you stand up against the flag, it's going to be perceived something," Sherman said. "Obviously Jeremy doesn't stand against those who sacrifice for this country or anything like that. He obviously understands the guys who have made the greatest sacrifice for our country and our freedom, but he also understands the oppression that our country has put African-Americans and minorities through for years.
"So yeah, I think that is something that they are trying to get recognized and looking for people to make a change too. Even with all of this, you are getting African-American veterans reaching out and saying that they have been discriminated against even in the service, so I think this discussion that Colin started is going to evolve into something deeper."
Seahawks coach Pete Carroll did not know Lane was going to sit during the anthem but spoke with the cornerback in the locker room after the game.
"It's totally an individual decision, but these are very interesting issues that we're dealing with right now," Carroll said. "Our team has been working at it, and we've been in the process of communicating about a lot of stuff right now. That was an individual thing. But I'm really proud of the progress we're making in the conversation, and I look forward to continuing it with our guys.
"It's really important to us to understand and to be smart about what we're doing and how we handle our business. Like I've been telling you, we have a great group of guys that lead this team, and they're going to help us as we move forward. I'm very much in support of them and how we handle it. This was an individual statement tonight.
"The individuals in this program have always been very crucial to us, and recognizing them. This is another time we support our guys."
ESPN.com's Paul Gutierrez contributed to this report.