Also, New York reduced the protection on a 2016 second-round draft pick it sent to Portland in 2012 and the Kings later acquired from the Trail Blazers.
Knicks general manager Steve Mills said the deal helped better balance New York's roster, which was heavier at shooting guard but not deep at small forward behind Carmelo Anthony.
The 6-foot-9 Outlaw has career averages of 8.5 points and 3.2 rebounds in 622 games in 11 seasons with Portland, the Los Angeles Clippers, New Jersey and Sacramento. Last season for the Kings, he averaged 5.4 points and 2.7 rebounds in 63 games.
The 6-7 Acy averaged 3.1 points and 3.2 rebounds in 92 games in two seasons with Toronto and Sacramento. Last season, he averaged 2.7 points and 3.4 rebounds in 63 games for the Raptors and Kings.
''I just think he adds a level of energy that we think is missing when we look across the roster, and we think he can be helpful there,'' Mills said on a conference call.
''With Travis, he's a veteran, which we like. He can shoot the 3-ball, he's long and athletic, and we know he's a guy that has the capabilities to play behind Melo.''
Ellington has played five NBA seasons with Minnesota, Memphis, Cleveland and Dallas, averaging 6.4 points in 312 games. The 6-4 guard was acquired by the Knicks from Dallas on June 25.
Tyler has averaged 3.6 points and 2.6 rebounds in 104 games with Golden State, Atlanta and New York. The 6-10 forward averaged 3.6 points and 2.7 rebounds in 41 games for the Knicks last season.