The Golden State Warriors have the best record by a team in a season, with a record of 73-9 in 2015-16.

which team had the best regular season record in a season

TEAM	REC	SEASON	GP	W%	MPG	PPG	RPG	APG	SPG	BPG	TPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	MIN	PTS	REB	AST	STL	BLK	TOV	PF
Golden State Warriors	73-9	2015-16	82	.890	242.4	114.9	46.2	28.9	8.4	6.1	15.2	42.5	87.3	48.7	13.1	31.6	41.6	16.7	21.8	76.3	19,880	9,421	3,788	2,373	689	498	1,245	1,701
Chicago Bulls	72-10	1995-96	82	.878	240.6	105.2	44.6	24.8	9.1	4.2	14.3	40.2	84.0	47.8	6.6	16.5	40.3	18.2	24.4	74.6	19,730	8,625	3,658	2,033	745	345	1,175	1,807
Chicago Bulls	69-13	1996-97	82	.841	240.6	103.1	45.1	26.1	8.7	4.0	13.5	40.0	84.4	47.3	6.4	17.1	37.3	16.8	22.5	74.7	19,730	8,458	3,696	2,142	716	332	1,109	1,617
Los Angeles Lakers	69-13	1971-72	82	.841	240.9	121.0	56.4	27.2				47.8	97.5	49.0				25.4	34.5	73.4	19,755	9,920	4,628	2,232				1,636
Philadelphia 76ers	68-13	1966-67	81	.840	240.9	125.2	70.4	26.4				48.3	100.0	48.3				28.6	42.1	68.0	19,515	10,143	5,701	2,138				1,906
Boston Celtics	68-14	1972-73	82	.829	240.6	112.7	58.6	28.3				46.5	103.8	44.8				19.7	25.3	78.0	19,730	9,238	4,802	2,320				1,805
Golden State Warriors	67-15	2016-17	82	.817	241.2	115.9	44.4	30.4	9.6	6.8	14.8	43.1	87.1	49.5	12.0	31.2	38.3	17.8	22.6	78.8	19,780	9,503	3,643	2,491	785	555	1,211	1,585
San Antonio Spurs	67-15	2015-16	82	.817	240.3	103.5	43.9	24.5	8.3	5.9	13.1	40.1	82.9	48.4	7.0	18.5	37.5	16.4	20.4	80.3	19,705	8,490	3,601	2,010	677	485	1,071	1,433
Golden State Warriors	67-15	2014-15	82	.817	240.6	110.0	44.7	27.4	9.3	6.0	14.5	41.6	87.0	47.8	10.8	27.0	39.8	16.0	20.8	76.8	19,730	9,016	3,667	2,248	762	496	1,185	1,628
Dallas Mavericks	67-15	2006-07	82	.817	240.9	100.0	41.9	19.9	6.8	5.0	13.9	36.7	78.6	46.7	6.5	17.1	38.1	20.1	24.9	80.5	19,755	8,201	3,435	1,632	560	408	1,140	1,837
Los Angeles Lakers	67-15	1999-00	82	.817	241.5	100.8	47.0	23.4	7.5	6.5	13.9	38.3	83.4	45.9	4.2	12.8	32.9	20.1	28.9	69.6	19,805	8,267	3,855	1,921	613	534	1,143	1,841
Chicago Bulls	67-15	1991-92	82	.817	241.8	109.9	44.0	27.8	8.2	5.9	13.3	44.4	87.4	50.8	1.7	5.5	30.4	19.4	26.0	74.4	19,830	9,011	3,612	2,279	672	480	1,088	1,693
Boston Celtics	67-15	1985-86	82	.817	242.1	114.1	46.4	29.1	7.8	6.2	16.6	45.3	89.2	50.8	1.7	4.8	35.1	21.8	27.4	79.4	19,855	9,359	3,807	2,387	641	511	1,360	1,756
Washington Capitols	49-11	1946-47	60	.817	240.8	73.8		6.3				28.7	96.6	29.7				16.4	23.2	70.6	14,450	4,428		378				1,144
Miami Heat	66-16	2012-13	82	.805	242.4	102.9	38.6	23.0	8.7	5.4	13.9	38.4	77.4	49.6	8.7	22.1	39.6	17.4	23.0	75.4	19,880	8,436	3,166	1,890	710	441	1,143	1,533
Cleveland Cavaliers	66-16	2008-09	82	.805	241.2	100.3	42.2	20.3	7.2	5.3	12.7	36.9	78.7	46.8	8.0	20.4	39.3	18.6	24.5	75.7	19,780	8,223	3,460	1,663	593	435	1,045	1,663
Boston Celtics	66-16	2007-08	82	.805	240.9	100.5	42.0	22.4	8.5	4.6	15.2	36.4	76.7	47.5	7.3	19.1	38.1	20.5	26.5	77.1	19,755	8,245	3,445	1,833	696	379	1,246	1,864
Milwaukee Bucks	66-16	1970-71	82	.805	241.2	118.4	53.0	27.4				48.4	95.2	50.9				21.5	29.0	74.2	19,780	9,710	4,344	2,249				1,847
Syracuse Nationals	51-13	1949-50	64	.797	243.1	84.8		23.0				29.2	82.4	35.4				26.4	37.4	70.6	15,560	5,429		1,473				1,833
Houston Rockets	65-17	2017-18	82	.793	240.9	112.4	43.5	21.5	8.5	4.8	13.8	38.7	84.2	46.0	15.3	42.3	36.2	19.6	25.1	78.1	19,755	9,213	3,564	1,767	699	392	1,135	1,597
Los Angeles Lakers	65-17	2008-09	82	.793	241.2	106.9	43.9	23.3	8.8	5.1	13.5	40.3	85.1	47.4	6.7	18.5	36.1	19.6	25.5	77.0	19,780	8,768	3,602	1,908	718	420	1,103	1,698
Los Angeles Lakers	65-17	1986-87	82	.793	240.6	117.8	44.4	29.6	8.9	5.9	16.6	45.6	88.4	51.6	2.0	5.5	36.7	24.5	31.1	78.9	19,730	9,656	3,642	2,428	728	482	1,358	1,853
Philadelphia 76ers	65-17	1982-83	82	.793	241.8	112.1	47.9	24.6	9.9	7.0	19.8	43.9	88.0	49.9	0.3	1.3	22.9	24.0	32.3	74.2	19,830	9,191	3,930	2,016	812	577	1,627	2,041
Boston Celtics	59-16	1959-60	75	.787	241.0	124.5	80.2	24.7				49.9	119.6	41.7				24.7	33.6	73.4	18,075	9,337	6,014	1,849				1,856
Boston Celtics	64-18	2023-24	82	.780	241.8	120.6	46.3	26.9	6.8	6.6	11.9	43.9	90.2	48.7	16.5	42.5	38.8	16.3	20.2	80.7	19,830	9,887	3,799	2,207	557	538	979	1,326