A Southern California native who starred in college at UC Santa Barbara, Pontius returns to his home state after spending seven seasons with D.C. United and the past two years with the Philadelphia Union.
The 30-year-old has made 222 appearances over nine MLS seasons, compiling 46 goals and 29 assists. Pontius earned MLS Best XI honors in 2012 and was named the league's Comeback Player of the Year in 2016, when he recorded 12 goals and six assists in his first season with the Union.
Pontius saw his production decline during his second season in Philadelphia, though, as he notched two goals and six assists in 30 matches.
He has earned five caps for the U.S. since making his debut in January 2017, including three appearances as the Americans won the CONCACAF Gold Cup title last summer.
"Chris is a proven and experienced player in our league who can bolster our roster immediately," Galaxy coach Sigi Schmid said in a news release. "He is a Southern California native who will be a valuable addition to our squad both on the field and in the locker room. We look forward to him joining the team as we begin preseason training."
Most comfortable as a left-sided midfielder, Pontius also has experience playing on the right flank and up top. He joins a Galaxy attack that already experienced a shake-up Saturday, when the club acquired Norwegian striker Ola Kamara from the Columbus Crew in exchange for U.S. international Gyasi Zardes.
The Galaxy finished with a league-worst 8-18-8 record in 2017, while their 45 goals scored ranked 17th out of 22 MLS clubs.